5 Incredible Minerals Sold in an Auction

Feb 6, 2018

One of the best places to find high quality rare minerals is in an auction. Dealers bring their finest specimens forward for collectors to appraise and cast their bid to take home the prize. Now, with the internet connecting communities from around the world, online auctions like mineralauctions.com are making it easier than ever to bid for incredible rare minerals – bringing more diversity and excitement to the mineral world!

Mineral auctions are growing and sometimes we see news breaking sales of one of a kind minerals and purchases. To celebrate the spirit of mineral auctions and the sought-after minerals ever found, here’s a list of 5 incredible minerals sold in an auction:

The Rockefeller Emerald

The Rockefeller name is woven in the fabric of American history with the Standard Oil Co. Inc. of the 1900s and many other entrepreneurial achievements. Adding to the Rockefeller legacy is the most expensive emerald in an auction, at $305,00 per carat: The Rockefeller Emerald.[1]

The 18.04-carat Rockefeller Emerald was purchased by Harry Winston for $5.5 million at the Christie’s Auction house in New York, New York. The Rockefeller Emerald was first acquired by John D. Rockefeller Jr. in 1930 as a center stone for a brooch. In the 1940s, the emerald was placed into a platinum ring. Images and more details available here.

The Sunrise Ruby

Original work: Société Cartier; Depiction: Justin Tallis Sunrise Ruby - one of the most valuable gemstones sold at auction - weighs in at 25.59 ct. Cartier Photo.

Rubies are one of the rarest minerals in the world with valuable qualities that are increasingly hard to find in nature. As a red variety of corundum, rubies have an intense red color that come from their chromium impurity, separating them from their sapphire cousins. Large carats of rubies are exceptionally rare, so it should be to no surprise that a 25.59-carat ruby called, “The Sunrise Ruby” sold for a record of $30.33 million at Sotheby’s in Geneva.

Praised as “amongst the rarest of all gemstones” by David Bennet, head of Sotheby’s international jewelry division, The Sunrise Ruby is one of the few rubies in the world to have the rare grading of pigeon’s blood color at its size.[2]

Blue Moon of Josephine

Described as “flawless” by the gemstone world, the 12.03-carat Blue Moon of Josephine was auctioned for $48.5 million at Sotheby’s in Geneva.[3] The diamond was bought by Joseph Lau, a billion from Hong Kong, as a gift for his daughter. The Blue Moon of Josephine is an exceptionally rare blue diamond with a hue described as Fancy Vivid by the GIA. Fancy Vivid describes a gemstone whose medium to dark tones are strongly saturated and have only been found in 1% of all blue diamonds.[4] Photos here.

Oppenheimer Blue Diamond

While the Blue Moon of Josephine broke records for being one of most expensive blue diamonds per-carat ever auctioned, at $4 million per-carat, the record for most expensive blue diamond ever auctioned goes to the Oppenheimer Blue. The 14.6-carat blue diamond was auctioned at Christie’s in Geneva for $57.5 million, making it the largest Vivid Blue diamond sold at an auction.[5]

The Oppenheimer Blue diamond was named after Philip Oppenheimer of the De Beers Diamond Jewelers. Blue diamonds are an exceptionally rare type of diamond with only 10% of all found blue diamonds being larger than a carat.[6] The Oppenheimer Blue is truly a one-of-a-kind gem with qualities that place amongst the rarest of the rare. View the amazing photos here!

Pink Star Diamond

Earlier this year, the attendees of Sotheby’s in Hong Kong witnessed history as the world record for the most expensive gemstone ever sold at auction took place. The 59.6-carat Pink Star Diamond, a diamond recognized as the largest Internally Flawless Fancy Vivid Pink by the Gemological Institute of America (GIA), sold for $71.2 million.[7]

According to Sotheby’s, The Pink Star Diamond was mined by De Beers in Africa in 1991 and was 132.5-carats. The rough diamond was then “meticulously cut and polished over a period of two years.” View the results!


Want to stay up-to-date on the latest news and events about the mineral world? Register for the Arkenstone’s mailing list for information on the latest findings, news, and many mineral show announcements throughout the year!

We’ve recently updated our galleries with many impressive specimens from around the world. You can find our latest collections here.

[1] Roberta N. “Harry Winston Pays $5.5 Million For Rockefeller Emerald: Most Expensive Per-Carat Emerald Ever Sold”. Forbes. https://www.forbes.com/sites/robertanaas/2017/06/21/harry-winston-buys-worlds-most-expensive-emerald-at-auction-5-5-million-rockefeller-emerald-christies-auctions-highest-priced-emerald-world-records-for-emeralds-john-d-rockefeller/#39e7b5c464b2

[2] “This ‘pidgeon blood’ ruby sold for a record $30 million’. Business Insider. http://www.businessinsider.com/afp-pigeon-blood-ruby-sells-for-record-30-million-2015-5

[3] “Tycoon buys $48m blue diamond at auction for daughter”. BBC. http://www.bbc.com/news/world-europe-34795005

[4] “World Auction Record Price-Per-Carat for a Diamond or Gemstone”. Sotheby’s. http://www.sothebys.com/en/auctions/ecatalogue/2014/magnificent-jewels-and-noble-jewels-ge1505/lot.513.html

[5] “The Oppenheimer Blue”. Christie’s. http://www.christies.com/features/The-Oppenheimer-Blue-Diamond-7197-3.aspx

[6] Cecilia J. “’Oppenheimer Blue’ diamond sets new record, fetches $57 million”. Mining. http://www.mining.com/oppenheimer-blue-diamond-sets-new-record-fetches-57-million/

[7] Merrit K. “’Pink Star’ Diamond Sells for $71 Million, Smashing Auction Record”. NPR. http://www.npr.org/sections/thetwo-way/2017/04/05/522739361/pink-star-diamond-sells-for-71-million-smashing-auction-record

The Rarity of Tanzanite

Jan 17, 2018

By Robert Gessner BSc GG, Gessner Gems
Reprinted with express permission from the author

In 1967, blue-violet crystals of the mine- species, zoisite, were discovered south of Mount Kilimanjaro in northeast Tanzania. The host rocks of the discovery, which are orders of magnitude older than Africa’s highest mountain, form part of the Lelatema Mountains which are located very near the town of Merelani. In 1968, Henry Platt of Tiffany & Co. christened the new and remarkably beautiful zoisite gem,Tanzanite, to honor its single-source discovery in Tanzania. The 50th anniversary of its discovery is marked in 2017 and is the most notable and exciting event of the gemstone industry of the 20th Century.

Bright blue tanzanite crystals are rarely found in sharp crystals like this. Orthorhombic crystal termination seen on the blue axis of a Tanzanite crystal. Robert Gessner Photo.

What makes this gemstone even more interesting and unique, and sets this beautiful stone apart from all others, is its remarkable rarity. Crucial in understanding its rarity is that this stone is the only one (or, one of the few) that evolved from a collector’s stone, only available to a few, to a commercially available stone. But this is only for a limited time: our generation. Tanzanite is found and mined in only one place on earth: a 7 square km area that outcrops near the town of Merelani in northeast Tanzania.

View of Mount Kilimanjaro from Block C overlooking Block D. Robert Gessner Photo

It is found in only one place on earth because of a very complex and unique set of geological conditions that came together during the breakup of the supercontinent, Gondwana, between 1.5 and 2.5 billion years ago. My intention is to not get too technical, but the geological origins are so interesting, and for me, the start of the story that I want to share, creating excitement for current and future owners and highlighting the fact that this gemstone is only available for a single generation: our generation.

The most striking feature of Tanzanite is its color. Or colors. It is a pleochroic gemstone. More specifically, a trichroic gemstone simply means that it naturally displays a different color in each direction, or on each axis.The fine crystals display intense, well-saturated and deep colors. The color-causing element (or chromophore) of Tanzanite is vanadium. Think of it the same as the element chromium giving Rubies their red color. The vanadium is responsible for the blue-violet color in Tanzanite. If any geological history needs to be mentioned, it is this because the rare availability of the vanadium during Tanzanite’s formation is what ultimately is responsible for what makes this gemstone so beautiful, desirable, and popular.

Tanzanite crystal in a pocket in Bravo Shaft. Robert Gessner Photo.

The vanadium is a trace element that came from the organic (tree and plant) material that was deposited with eroded silica-rich sands and calcium-rich (shell and ocean-life) material in a deltaic/shallow sea environment over millions of years during the gradual break up of Gondwana.This accumulation of layers was subsequently buried and metamorphosed at high temperatures and pressures.The organic material became graphite, the silica-rich sands became the schist and gneiss, and the calcium-rich material became dolomite (an impure marble). All these rocks are seen in the deposit.

At 500 million years, a geological event resulted in the crystallization of Tanzanite. Erosion on the surface on the earth and the natural upliftment of continental crust (in respect to the denser and heavier oceanic crust) brought this deposit to the earth’s surface where Tanzanite was found for the first time in 1967.

Pocket containing Tanzanite in Bravo Shaft. Robert Gessner Photo

The transition from a collector’s stone to being commercially available started in earnest in the late 1990s when the Tanzanian government started adequately regulating the deposit by subdividing the 7-kilometer section into Blocks A, B, C, D, and D-Extension, respectively, and granting mining licenses to companies and individuals at different levels of investment ability. Block C, the largest 2 km 2 of the 7 km 2 , was awarded to African Gem Resources Limited (Afgem), a private South African company, after winning the tender in 1998. Only in the early 2000s did the company start investing heavily in geology and mining as production was decreasing and becoming more haphazard after an initial and significant bulk sample that raised millions of dollars for Afgem.

The investment in geology and mining resulted in a better understanding of the deposit’s geology and the Tanzanite-bearing structures, and in turn increased the company’s production. The increased production resulted in increased revenues that were put back into the mining. More shafts were sunk, more mining faces were created, and from a geo - logical point of view, more geology was exposed on the sidewalls. With all this work, a geological model was created, as well as an understanding that was never in place before. Another result was production areas could now be proactively planned as opposed to a history of reactive mining. Essentially, we were able to get the mining into the right places. As a result, from 2005–6, production from the company improved to more consistent commercial volumes. It must be noted that at no point can a geologist predict the gemstone; we are always predicting the geology in which the gems are formed. From mid-2000, the consistent production from the mine was a result of having the mining faces in the right areas. If one face was not producing, another one was.

In late 2004, Afgem become a publically traded company, TanzaniteOne Mining Limited (TanzaniteOne), and listed on the London Alternative Market (AIM).

Self-portrait taken August 2005 from the largest pocket of Tanzanite I have seen in the deposit! Robert Gessner Photo.

Large-scale mining operations generate not only more production volume, but also more volumes of all grades, more consistently. As a result, a master grading set was created. For the first time, rough Tanzanite could be parceled for size, colour and quality to its sightholders. By definition, this system of product presentation for rough sales could only work with regular and good volumes of production from the mine. This was a direct result of the size of the deposit being professionally mined, with regular production and future exploration.

Afgem initially, but then TanzaniteOne, took a collector’s gemstone to one that became commercially available around the world. But the story does not end there. Because it is commercially available does not mean that Tanzanite is any less rare than it originally was. It just became accessible to everyone; but only for a limited time: our lifetime. Found for the first time in 1967, it can be estimated that the gemstone will no longer be accessible, particularly commercially, within a single generation of its discovery. The most common understanding of this is that the deposit gets physically exhausted (mined out), but the actual concept is that the costs to mine become too high versus the income from sales (i.e., the gemstones are still in the ground but are physically too deep to mine–too expensive). This factor highlights its generational rarity, which the current market and value of Tanzanite do not indicate. The market and consumers think that because there are high volumes of Tanzanite available at the moment this will continue; but this not the case.

The current prices of Tanzanite, particularly at the wholesale level, are actually too low; too low for how rare the gemstone is, and too low for future mining. The amount of Tanzanite on the market currently should be seen as a bubble and temporary; it will not continue. There has been a lot of recent supply due to many miners being in the right areas and producing, with this product subsequently making it to the wholesale market. This is the reason for the low wholesale prices, but with the mines getting deeper, and the natural pocket effect of Tanzanite, this will not continue. The reality is that the deeper the mines get, the more expensive it will be to mine. For future years of supply, the wholesale prices need to increase.

Tanzanite crystal in Main Shaft. Robert Gessner Photo.

Single generation is a phase coupled with Tanzanite since its marketing in the 2000s, and this itself, evokes its own romance, beauty and rarity. Trying to tie the availability to a number of years should not be the discussion point, and according to me, less importance and significance should be given to it. The history of the talk of only available for another 10 years, or 15 years ties in to large-scale public mining at companies attempting to quantify its resource for value purposes and investment, which the previous owners in the 2000s took to the market to create desire and indicate its rarity. There are too many factors that affect a number like this, so it should only be seen as guide and less importance should be given to it. No one asks how many years are left of the Colombian emerald deposit, or the Burmese Ruby deposit. It cannot be defined, so why should the Tanzania Tanzanite deposit be defined? The famous Brazilian Paraiba Tourmaline and Russian Demantoid Garnet deposits are now mined out, and very little or no material is available anymore; nothing significant in recent years anyway. Old stock or old mined material that do become available command extremely high prices today. We can only look back and say that we should have bought then. This will be the same for Tanzanite. Buy now, as the prices are low–for the moment. All gemologists know that Tanzanite is trichroic. It is also part of the orthorhombic crystal system. As Tanzanite extracted from the earth is often in its perfect rectangular crystal shape, it is easy to see its trichroism (meaning you can see a color on each axis, or side of the gemstone). These natural rough crystals can show either a 3-colour trichoism combination of blue, violet, and brown (combination of red/yellow/green) or a 3-colour trichroism combination of blue, violet, and violet (so two violet axes, or sides), respectively. The reason for the two combinations of trichroism is due to natural (in the ground) heating that a percentage of the natural crystals were locally subjected to. The natural heating has removed the original red/yellow/green on the “brown” axis to colorless, and so the (second) violet color is seen. Technically, this has been achieved by an intervalance charge transfer during heating of Ti3 + to Ti4 +, which is colorless. [As all chemical equations require balance, the second change is a slightly stronger blue-violet (so the V4 + to V3 +). The colour change due to heating is a stable change. As this heating takes place naturally, it is impossible to distinguish between post-extraction (or by man). The result of this means that there are only two realities to label a tanzanite gemstone: no heat or no heat treatment by man. The first is that the gemstone in question displays its blue, violet, and brown trichroism, and the second condition is that a strict and traceable provenance of no heating by man exists of a blue, violet, and violet trichroism gemstone directly from the earth, through the trade to the wholesaler/retailer.

Trichroic pleochroism of Tanzanite under incandescent light. Robert Gessner Photo.

This second condition may be a potential option but is strictly tied to a person’s honesty, because it is scientifically impossible to prove. Another wonderful and valuable characteristic of Tanzanite is that there is only natural Tanzanite in existence. Man cannot create Tanzanite due to its unique formation in the earth and its chemistry. Imitations, by definition any material that looks like a natural gem and is used in its place, do exist but any trained gemologist would be able to confirm whether it’s natural or not with a few simple gemological tests. Tanzanite is a rare gemstone with both a remarkably unique geological history and a success story in the jewelry market and in our homes; a story of rarity that needs to be shared; a story that is hidden within each piece of Tanzanite worn by its owners.

By Robert Gessner BSc GG,Gessner Gems

Article as published in AGTA Prism, Volume 4, 2017, viewable online here.

Article adapted from its original as it appeared in the GemGuide, Gem Market News, November/December, Volume 36, Issue 6 published by Gemworld International.


About the Author: I am geologist by profession having completed my BSc Degree in Geology at the University of Cape Town (UCT), South Africa, in 2002, and completed my post-graduate Honors Degree at the University of Stellenbosch, South Africa, in 2004. My first colored gemstone industry opportunity was in Tanzania in 2003, which has become my specialization and career. I have over 13 years of colored gemstone geology and mining experience in East Africa working specifically with Tanzanite, Tsavorite, Zambian Emerald. In 2016, I graduated as a Graduate Gemologist (GG) from the GIA in Carlsbad, USA. Today, I am based in Los Angeles, and have my own business offering consulting, training and gemstone sourcing. www.gessnergems.com

The New iRocks.com

Jan 8, 2018

Mineral lovers-

We're excited to bring a new iRocks.com experience to the web with improved features, faster speeds, and mobile responsive design for mobile and tablet users.

Start off by registering using the button in the top right.

Once you finish creating your account and logging in, take advantage of the new wishlist feature (click the purple heart when you're browsing specimens) so you can create your own virtual collection, track specimens to see if they go on sale, and easily access your favorite saved minerals.

If you're looking for a good place to start browsing our minerals for sale, visit our galleries of newly added specimens or visit our themed galleries.

If you are looking for a specific mineral, our search engine can narrow down the hunt by species, locality, size, and more!

As always, if you're looking for a specific specimen that doesn't appear online, don't hesitate to get in touch with us at info@irocks.com, since we have a wide range of inventory here in our new headquarters in Dallas.

Rock on, Mineral Lovers!

The New Arkenstone Gallery

Jan 4, 2018

2017 brought a lot of changes to The Arkenstone. We added a new full-time employee (hi Tom Campbell!), purchased several new collections (have you explored the Kay Robertson selections?), but most significantly, we moved to our new headquarters featuring over 7,000 square feet of mineral display space and plenty of other new features for new enthusiasts and long-time mineral lovers.

Lobby Entrance

Lobby at The Arkenstone Gallery of Fine Minerals Large decorative pieces, important lapidary art (lapis), and amethyst are featured in the front lobby.
A pair of backlit Persian onyx slabs totaling 2,200 pounds and nearly 6,000 pounds of reclaimed 150-yr old Northeastern red oak timbers line the mine shaft "Portal" into the gallery.

The Collector Gallery

Display cases of fine minerals in the Wood Room
Fine minerals from around the world are for sale in the gallery.

Gem & Jewelry Salon

Our new Gem & Jewelry Salon is ready for visiting jewelers for events and trunk shows.

The Jewelry Salon connects natural crystals and the wearable art that results.
Paula Crevoshay displayed her impressive jewels at our Grand Opening

The Design Showroom

If you're looking for larger home or office accents, visit our Design Showroom.

The Museum Gallery

The Trophy Room

Sleek black pedestals display large museum-sized specimens.

Sleek black pedestals display top collector specimens.

The Book Store

Add to your library with our selection of literature, including rare and out-of-print volumes, periodical issues, DVDs, and more. Looking for something specific? E-mail us at info@iRocks.com.

If you're in the Dallas area, send us an e-mail to schedule your private visit to info@iRocks.com.

Tips for Buying Rare Rocks and Minerals Online

Dec 23, 2017

A major part of being a mineral collector is building relationships with vendors and hunting down the best specimens. Chances are you’ll want to grow your collection over time, and there are plenty of online vendors with vast collections to choose from. With so many options, how do you know which online vendors to focus on?

Here are a few tips to help you find a great online vendor:

Tip #1: Stay Informed About Your Specimens

Before deciding on a vendor, it’s important to have a clear idea about the rare rocks and minerals that you want to add to your collection. There are many species to choose from, each with unique properties, colors and luster that all work into its price.

If you’re unsure about what rare rocks and minerals you want to start your collection, look at complete exhibits and make a list of species that capture your interest. You’re likely to trade and upgrade your collection overtime, so feel free to experiment with your interest. For example, you may start your collection with a type of quartz crystal and move into rarer species months or years down the road.

Chinese minerals from Mount Xuebaoding in Sichuan Province often have a deep orange color. Gemmy clear quartz and muscovite accent an orange scheelite crystal.



Tip #2: Look at the Display

When shopping online, the best vendors will have a professionally taken photograph for each of their specimens. You’ll want to be weary of vendors who use generic photographs, as mineral colors can vary depending on lighting.

Take into consideration how the specimen will fit into your existing display space. If you’re using a glass cabinet, use the photograph provided as a reference to see if you like how well it sits with your collection.

Keep in mind that you’re free to ask the vendor for other photographs of the piece for sale. For example, crystalline structures can come in many shapes and clusters. Looking at the specimen from different angles can help you determine if it fits with your collection.

In fine mineral photography, it's often necessary to take many pictures in your quest to produce the best fine mineral photographs. Sometimes photos showing multiple angles of a specimen help determine if the piece is a right fit.


Tip #3: Be Intentional about Building Relationships with Vendors

After researching species and are settling on a budget, you’ll be more informed and comfortable shopping for your collection. You can shop from an online catalog, specialized vendors, a club’s collection or an exhibit.

Well-established vendors will have variety in the specimens available for you to choose from. When getting to know an online vendor, look for their archive of specimens and any published work. This will give you an idea of the types of species that they specialize in, helping you with price bargaining.

The key is to build relationships with these vendors. Over time, they’ll add new species to their collections and you’ll be on the shortlist of people to contact before specimens go on sale.

Tip #4: Look for Detailed Specimen Descriptions

The single most important feature in any online sale is a detailed description about the specimen. Information about a specimen's size, properties, condition, and origin should all be available to the customer.

For example, benitoite is a rare barium titanium silicate mineral that has grown in popularity for its deep blue, purplish colors. Authentic specimens of benitoite are only found in the mines of San Benito County, California. Knowing where a specimen comes from can have a major influence over its described authenticity and price.

Benitoite crystal from Dallas Gem Mine area in San Benito, California. Copyright The Arkenstone, Joe Budd Photo.


Tip #5: Know Where You’re Shipping From

Understand that rare rocks and minerals can get heavy and shipping prices can go up, depending on where it’s being shipped from. Keep in mind that exceptionally fragile specimens may find it more challenging to ship, and the vendor may recommend that you pick it up in person.

Some vendors will go to various mineral shows, showing their collections in exhibits and galleries. Keep track of vendors who are hitting the road and inquire about picking up your specimens along their travels. The Arkenstone is flexible with bringing specimens for delivery at shows in Denver, Tucson, Munich, and even China! Plus we host a semi-annual San Francisco Road Show.

There are many great online vendors that sell expansive collections of rare rocks and minerals. The hobby is also made of many close communities and clubs where rockhounds come together and talk about each other’s collections. Ask your fellow club members or rare rock and mineral collecting clubs about any vendors that they recommend.


Our favorite learning opportunity is the annual Dallas Mineral Collecting Symposium, sponsored by The Arkenstone and friends. The symposium will feature an expert speaker series about word-famous collections and also provide opportunities to mingle with top mineral dealers, collectors and enthusiasts.

Don’t forget to check our listings for our other shows. The Arkenstone is proud to offer specimens in many displays around the world.


Art Soregaroli: October 19, 2017

Oct 20, 2017

An introduction of Dr. Art Soregaroli's Fine Mineral CollectionWe learned with great sadness of the passing of Art Soregaroli on October 19, 2017. The Arkenstone acquired his collection several years ago, and he took a few moments to share some of his thoughts with us. They are shared here, below, along with a personal note from Peter Megaw.

"The mineral specimens you see here now have been liberated from my collection of the past 6+ decades, rescued from my favoured lair in the recesses of a Vancouver home sold and slated for demolition. This move has forced my hand to make the difficult decision to find new homes for these many precious friends I have spent a lifetime collecting.

From my early youth, collecting agates and arrowheads in rural Iowa quarries and stream beds, to kicking up rocks with pack mules in Idaho as a graduate student, to my doctoral work at the University of British Columbia in Canada (where I’ve made my home this past half-century), and throughout the career that followed in exploring the world for precious metals and commodities to mine, I’ve rarely met a specimen I didn’t like. And, as much as each specimen holds a special place in my heart, I suppose what I am most grateful for in having been captivated by this esoteric hobby is the people I have met who share my passion for minerals and geology, and the many friendships that have been forged at the rock-face, at the bargaining table, with the Mineralogical Record and at Tucson, and in peering through the glass of a display case.

So, now, as I continue my journey, I hope these specimens will continue theirs and bring joy and gratification to the ardent mineral collectors fortunate enough to make them their own."

-Dr. Art Soregaroli


"Sadly, Art passed away peacefully surrounded by family on October 19, 2017.  With his passing the mineral world lost a great geologist/mineral scientist, staunch friend and true gentleman - the outpouring of tributes from those whose lives he touched has been impressive.  His work getting the Pinch Collection to the Canadian Museum of Nature was mentioned by many, as was his work with the Brittania Mine mining museum near his home in British Columbia, and his manifold contributions to mineral symposia...especially the Pacific Northwest FM Symposium that closed just 2 days before his passing. Jodi Fabre noted that Art was single-handedly responsible for guiding the famous Panasquiera Mine in Portugal back into the black so that could not only thrive as a metals mine, but continue to produce quantities of excellent specimens to this day.

Those who wish to express condolences to the family can do so to his beloved wife Rosalie remembering.art@gmail.com.  She will share them with daughter Carla, son and daughter in law Brian and Michelle and the grandchildren he doted on so fondly.

Those who wish to honor his memory can do so by visiting/supporting the Canadian Museum of Nature, the Brittania Mine Museum or attending next year's Pacific Northwest FM Symposium.  Adding a specimen from Panasquiera to your collection would work too!"

- Dr. Peter Megaw


Peter Megaw's original tribute (published in 2015) is available here.

Have stories about Art that you'd like to share? E-mail them to info@iRocks.com, and we will happily add them here.


View Art Soregaroli's Collection

How to Grow a Valuable Mineral Collection

Sep 9, 2017

Collecting rare rocks and minerals is like jumping into a time machine that lets you look back at the journey of Earth. Under high heat, pressure, and the watchful eye of time, rare rocks and minerals are born with an array of unique qualities that make the hobby exciting. Although massive collections are extraordinary things to look it, they can also come with a lot of work.

A spectacular case of fine minerals, gems, and jewelry from The Arkenstone at a private gallery show.

Whether you’re new to the hobby or a seasoned rockhound, it’s a great idea to plan the direction of your collection. Planning your collection will help you stay organized and maintain its value as you take on new specimens. As members of the rare rock and mineral collecting community, we’re always glad to offer insightful information about expanding the value of your collection.

Find What Interests You

The key to building a valuable collection is understanding the qualities about rare rock and mineral collecting that interests you. Take advantage of the many online publications and open field guides available to learn more about the types of rocks and minerals available. Are you collecting specimens of a specific family? Perhaps you want to focus your collection on origin or know a gemologist whose work you’d like to follow? Here are some publications to consider when doing research:

Custom engraved bases by The Arkenstone, www.iRocks.com, are one of the most important ways to boost the display beauty of your fine minerals. Fine minerals not only benefit from well-lit cases. Having the appropriate bases can help orient your specimens well, and they are much safer!

Dedicate a Space for Your Collection

Find a comfortable space in your home to show off your collection. Keep in mind that some rare rocks and minerals are reactive to sunlight and moisture. For example, some specimens of photochromic crystals like Kunzite permanently lose their deep pink color when exposed to too much sunlight.

You may want to consider investing in a front-window cabinet or display case to protect your specimens. Rare rocks and minerals like SulfurEttringite, and Dioptase are fragile and can break if dropped or mishandled. By keeping them in a cabinet or display case, your collection will be safe in homes with small children and pets.

Know What to Look for On a Hunt

As your collection grows, you’ll want to start trading and selling less valuable rocks and minerals for rarer specimens. If you’re new to collecting, it’s likely that you have pieces of damaged crystals, rocks or gems. It can be difficult to spot damaged specimens early in your collection, but as you learn more curating and build relationships with dealers, you’ll gradually add more value to your collection.

More experienced collectors will want to find better quality specimens to replace less valuable ones in their collection. Some of the criteria that collectors use in evaluating the value of a specimen are:

  • Size and Color
  • Rarity
  • Associated Minerals
  • Luster and Transparency
  • Damage and Repairs
  • Locality, History and Provenance

Before you invest in a specimen, you’ll want to make sure that you have documentation of its locality, as the country and mine can be significant in determining value. There are many specimens in circulation that are poorly documented, so they might not be appreciated for provenance as much as they deserve.

Join a Community and Visit Collections

Collecting is more fun with a group of enthusiastic rockhounds. Consider joining a collector club for access to field trips, newsletters, socials and professional services. Most collector clubs visit mineral shows, symposiums, auctions and rare exhibits together to learn more about other collections.

The Arkenstone participates in mineral shows around the world, and we also are the founding sponsor of the Dallas Mineral Collecting Symposium. The annual symposium held each August features world-renowned speakers to share their latest collections and experiences in the field.

Don’t forget to check our listings for our shows. We’d love to meet with you and talk about the various collections!

5 Favorite Rare Minerals

Aug 23, 2017

Collecting rare minerals is a passion that requires a lot of patience. Many specimens have journeys that last millions of years until a brave explorer takes the plunge and unearths their beauty. While all minerals are precious, there are a few that stand a cut above the rest in rarity, history and value. Here’s a list of 5 of our favorite rarest minerals.


Found exclusively in the foothills of Mount Kilimanjaro, the Tanzanite is one of the rarest minerals on Earth. In fact, it carries the saying, “1,000 times rarer than the Diamond”, to signify its limited supply. The Tanzanite’s history is young as it received its name from New York jeweler Tiffany & Co. in 1968.[1]

The formation of the Tanzanite crystal started roughly 600 million years ago as Mount Kilimanjaro erupted and created the unique conditions needed to form the crystals deep within the Earth. Starting at a brownish hue, the gorgeous blue-violet colors of the Tanzanite can be seen after the small amounts of the Vanadium impurities are heated and oxidized.


Blue Tanzanite Crystal. Copyright The Arkenstone, iRocks.com. Joe Budd Photo Tanzanite from the Merelani Hills of Tanzania. Copyright The Arkenstone, iRocks.com. Joe Budd Photo.


First discovered in 1907 near the headwaters of the San Benito river, the Benitoite is a blue-violet mineral whose gemstones are rarely found over 1-carot.[2] Found exclusively in California, Benitoite became the State’s official gemstone in 1985.[3]

The Benitoite is also known as the “blue diamond”, holding a sapphire blue color due to its small amounts of iron. However, rare specimens of Benitoite can come in an array of colors when exposed to UV light. Some Benitoite crystals will appear as a reddish color when shown under a long wave UV light with slight dispersions of green.

Benitoite crystal from Dallas Gem Mine area in San Benito, California. Copyright The Arkenstone, Joe Budd Photo.


Named after the Russian Czar Alexander II (1818 – 1881), the first Alexandrite crystals where discovered near the Tokovaya River of the Urals in 1834.[4] According to legend, Alexandrite was found on the day that Alexander II came of age to become the future Czar. With the crystals shining red and green, Alexandrite became a national favorite of imperial Russia.[5]

Alexandrite is known for its optical ability to suddenly change color under the faintest of light. Under daylight, the gemstones shine a deep greenish blue color, but under incandescent light it turns into a soft purplish-red color.

Color-change alexandrite from Zimbabwe Alexandrite shows different coloring under different light. Copyright The Arkenstone, iRocks.com. Joe Budd Photos



First discovered in the Mogok region of Myanmar (Burma) in 1951, the Painite was named after British gemologist Arthur Charles Davy Pain.[6] The Painite was once regarded as the rarest mineral on Earth with only 2 faceted gemstones found until mid-2005.[7] Although a few hundred crystals and pieces have been found to-date, nearly complete and facet crystals are extremely rare.

A few complete Painite gemstones that where found varied between brown to red-pink. It’s highly pleochroic, changing hues depending on the angle that you’re viewing it from.

Rare painite from Mogok, Burma (Myanmar). Painite is difficult to find in nature, especially with the delicate ruby association seen here. Copyright The Arkenstone, iRocks.com

Red Beryl

The Red Beryl, also known as the Bixbite, “Red Emerald” and “Scarlet Emerald”, is found in a few locations within the Thomas Range and the Wah Wah Mountains of Utah.[8] It was first discovered in 1904 and since then few quantities of Red Beryl have been large enough to form a gem.[9] This is because Beryllium rarely occurs in large enough quantities to produce the red coloring, making the Red Beryl incredibly rare.

The conditions needed to make the Red Beryl occurred around a hundred million years ago during the formation of the Rocky Mountains. Volcanic activity and Beryllium-rich gases created porous pockets of low pressure and high temperature, allowing the red coloring in the Beryl to settle.

Red Beryl var Bixbite (also called red emerald) from Wah Wah, Utah Red Beryls are extremely rare, and the important find in Utah has been closed for decades.



Since the mid-1990s, the Arkenstone has been a pioneer of the online mineral world, expanding the breadth of this hobby that we love worldwide. Grow your collection of rare and exotic minerals by exploring our online collection at iRocks! Click here to start your search or explore new collections in our Galleries.


[1] “Tiffany Colored Gemstones”. Tiffany & Co. http://press.tiffany.com/ViewBackgrounder.aspx?backgrounderId=35

[2] “California State Gemstone”. State Symbols USA. http://www.statesymbolsusa.org/symbol-official-item/california/state-gem-gemstone/benitoite

[3] Ibid.

[4] “Biography of Dr. Peter Bancroft”. Palagems. http://m.palagems.com/alexandrite-russia/

[5] Ibid.

[6] “Painite Visible Spectra (380 – 1100 nm)”. California Institute of Technology. http://minerals.gps.caltech.edu/FILES/Visible/painite/Index.html


[8] “Utah Gemstone Mining”. Geology. http://geology.com/gemstones/states/utah.shtml

[9] Ibid.

Opals: Stones of Many Colors

Aug 18, 2017

If there was a stone whose physical properties inspired magic, it’s likely to be a fine Opal. With the ability to reflect an impressive array of colors, it was thought that the Opal trapped fire and lightning. Today, the Opal is one of the most popular stones amongst rockhounds, jewelers, and historians.


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Unlocking the Mystery of Opals

Ethiopian opal with extreme color flash. Opal from Ethiopia weighing in at 88cts. Joe Budd Photo

Opal is a gem quality stone with the ability to intensely reflect an array of colors. They’re formed when silicon-dioxide enriched water, otherwise known as silica, permeates through the cracks of sedimentary rock. When the water-solution evaporates, the silica is left behind to gel and form an Opal stone.

Unlike any other species of rare rock, the Opal can display all the colors on a rainbow spectrum through a series of “moving” patterns. The most common colors shone are red, green, blue, and yellow with other color blends like pink and purple.

These colors are reflected by the diffraction of light entering the specimen, similar to the effect of a prism. The silica found within the Opal settle and layer randomly with many gaps in between. This allows white light to enter in an irregular array, diffracting and reflecting a different color.

The ability to reflect an array of colors is one of the rock qualities most sought after by great civilizations throughout history. The gorgeous display of reds, greens, and blues were thought to contain protective and medicinal properties, commanding a great value from jewelers and royalty.

Hyalite Opal, like this specimen from Hungary, shows shocking fluorescence under UV lighting!

The Opal: History’s Precious Stone

The Opal is one of the few precious stones whose origins trace back through several ancient civilizations. The name “Opal” derives from many world languages like the Sanskrit word, “Upala”, which translates to “precious stone”.[1] The name also has origins in the Latin word “Opalus” and the Greek word “Opallios”, both directly translating to “to witness a color change”.[2]

Historians trace the discovery of the Opal stone as far back as the Bronze Age. The Ancient Egyptians and Babylonians created protective talismans from Opals.[3] However, it wasn’t until the peak of the Roman Empire where Opals began circulation in markets with a value as high as Emerald stones. Opal stones were coveted by the Ancient Romans for their ability to shift colors at certain angles of light.[4]

According to an Ancient Roman legend, a wealthy Roman senator named Nonius owned a particularly fine Opal. The stone was rumored to have been as large as a hazelnut and valued at 2,000,000 sesterces.[5] Mark Antony, the ruler of Ancient Rome, heard of the stone and thought it would make the perfect gift for Queen Cleopatra of Egypt.

When the senator was approached about the stone, he refused to sell and fled Rome. This event led to Opals earning their prestige and value in the market through the modern era.

These very rare opal-replaced fossil shells were formed 135 million years ago and are unique to Australia. The supply at this famous locality, where the town of Coober Pedy is actually dug into the formation, has been exhausted as mining here is no longer profitable or commercially successful on any scale. Opal replacement of clam fossil from Coober Pedy, Australia

Australian Opals

Of the Opals mined, 95% come from Australia.[6] Other Opal producing countries include Mexico, Brazil, Ethiopia, and the United States.

Millions of years ago, the continent of Australia was covered by a massive inland sea that flushed silica enriched water into its sedimentary rock. Overtime, this silica enriched water would gel and form Opal stones throughout the continent.

In the early 1890s at the White Cliff mines, the first prospectors discovered pockets of fine Opal stone. Production of fine Opal at the White Cliff mines peaked in 1902 when 140,000 pounds of fine opal were mined and sold.[7] Other Australian mines like the Lightning Ridge and Coober Pedy were also found to contain fields of Opal stone. These discoveries cemented Australia as the leading producer of Opal stone around the world.




Opals have a fascinating history, and they continue to be a very popular precious stone. See our expansive collection of Opal stones and other rare rocks on our website! We’ve recently updated our galleries with many impressive specimens from around the world. You can find our latest collections here.

Also, don’t miss our listings for our rare rock and mineral shows. We’d love to meet with you and talk about the specimens in our collections!

[1] Gordon A, U.S. Department of the Interior, U.S. Bureau of Mines (Michigan: U.S. Department of the Interior, 1995), 19.

[2] Ibid.

[3] Lani S, Crystal Alchemy (Indiana: Xlibris Corporation, 2016), 192.

[4] “Opal History and Lore”. Gemology Institute of America Inc. http://www.gia.edu/opal-history-lore

[5] Allan E, The World of Opals (New Jersey: John Wiley & Sons, 1997), 58.

[6] Karen F. Atlas of Australia (International: Capstone Classroom, 2008), 24.

[7] “A Brief History of White Cliffs”. White Cliffs Opal. http://whitecliffsopal.com/html/history.html

From Rough to Refined: Exploring Gemstone Collections

Aug 13, 2017

While most gemstone buyers are seeking rough crystals in bulk, there are some rock and mineral enthusiasts who are simply interested in building a collection of beautiful stones. And, while we generally think of gems as the sparkling, finished stones displayed in fine jewelry, even rough crystals are often mesmerizing – each an amazing individual display of nature's fine craftsmanship.

From skillfully cut, jewel-quality gems, to rough crystal – one can find all kinds of material on the market. The question is, what makes a gemstone collection truly amazing?

Rough and cut aquamarine crystal. Joe Budd Photo.

As with all collectable items, the answer is somewhat subjective. What makes a collection really valuable is not necessarily it's cost, or the market value of the stones displayed – it is simply the level of interest it generates. And since, in this case, beauty is truly in the eye of the beholder – the door is wide open for building an amazing gemstone collection.

One of the special attractions of gemstones is that there are so many options for building an amazing collection. We've outlined a few ideas, here.

·      Collecting by color. One approach to collecting is to choose a particular color, and gather any high-quality rough crystals or gemstone specimens which most accurately represent that shade or hue. This allows the collector to showcase a wide array of species and varietals, while still maintaining a sense of cohesion between pieces.

·      Gathering the rainbow. Popular among collectors of both rough crystals and finished stones, the goal is to create a collection which features the full spectrum of shades and hues. This can create a stunning aesthetic when the collection is displayed in its entirety – mimicking a beautiful rainbow of color. It is also an effective way to highlight the beauty of gems and minerals which occur in a wide range of hues. A collection of beryls would create an amazing array for this type of collection.

·      Highlighting rarity. While most gemstones are considered valuable to some extent, there are certain varieties which are prized for their extreme rarity and beauty. A rare gems collection can be challenging to assemble initially – but the challenge of locating suitable specimens only adds to its inherent value, attraction, and intrinsic interest.

·      Celebrating diversity. Some collectors prefer to pursue one particular species or varietal, highlighting the similarities and differences occurring in rough crystals or cut specimens of the same type – especially those which are discovered in varying localities.

This collecting focus can be great for delving in-depth into the qualities or aesthetic features of a particular mineral or stone, and showcasing the beauty of its natural diversity. Tourmaline would be an excellent stone for this type of collection, as it exhibits stunning variation of color and feature, depending its area of origination – as would a collection of garnets.

  • Shape and cut. An in-depth examination of the different cutting styles and shapes of gemstones over time would make an interesting and educational historic collection – and can reveal some unusual insight into the presentation of various gems, and their use as jewelry or personal adornment.
  • Rough and cut collections. One of our favorite ways to emphasize the true beauty of gemstones, a “rough and cut” collection features both a rough crystal and cut stone for each specimen type. This allows the viewer to see both the raw, natural beauty of the uncut stone, and the brilliant, sparkling finished result – creating a gorgeously balanced, aesthetic display. (Really – the best of both worlds!)
This rare combo of rough danburite crystal and cut stone from Mexico shows the beauty of natural crystals and gem.

Whether your preference for collecting is broad or in-depth, specific to a particular species, locale, varietal, or color – the possibilities for defining your area of interest are limited only by your imagination. And, while some gemstones and rough crystals can be extraordinarily expensive, building an attractive gem collection need not require an enormous budget – simply a dedication to discovering and seeking out those specimens which add value and interest to your personal focus.

At the Arkenstone, we're big fans of celebrating the natural beauty of rocks and minerals – which means we often find a great deal of pleasure in examining rough crystals and stones. We also appreciate the contrast and insight offered by displaying rough and finished stones side by side. If you're interested in exploring this wonderful aesthetic, take a look at our current collection of cut and rough crystals – we know you won't be disappointed in these fine gemstone sets!