THIS IS A KILLER THUMBNAIL, of top, competition level quality! It is GEMMY - not just translucent, but really gemmy in the gemstone-can-be-cut-from-me sense. We estimate in fact that this termination, where it splays broadest, will yield several stones in excess of a carat that would be clean, almost unheard of for dioptase. The crystal is DOUBLY-terminated, and pristine at both ends, complete all around save for a small contact on the back, near the cerussite attachment. That cerussite sticking out serves as a natural pedestal to lean the piece diagonally and make it a large box-ffilling thumbnail, instead of a small miniature (which, it can be if upright). The gemminess and transparency on this thick crystal can be seen even in normal lighting, without need of a torch - which IS needed to make only the edges even remotely see-through on some of the best Tsumeb dioptases (which now pale in gemminess to these more recent finds). This piece is SHARP. It has riveting geometry, great luster, and that gemminess - plus a superb termination in an elongated style that is quite unique to this mine and dissimilar from classic dioptase crystals from Tsumeb, Congo, or Russia. I believe this mine will, someday, be remembered for producing the best dioptase crystals on a gram for gram basis of quality. For us, this was the most recent find represented in a small sequel of Charlie Key's collection which we bought in early 2008, but have been holding back to see what more would come from the mine. For my taste, as one last comment, I have seen many Tsumeb thumbnails I Can RESPECT, but none that simply mesmerized me like this one does, in quality and style.