Cuprite from this famous mining district in the Democratic Republic of the Congo is considered the best in the world for combination of luster, sharpness, and brightness internally. Here is a sharp single crystal to 1.5 cm across, perched beautifully in matrix, with a combination of all of those qualities in one specimen, rarely seen! Photos speak for themselves. It does require backlighting, but when lit well, it literally glows like a ruby. Pristine, this crystal cluster has literally the finest luster you can get in the species, a brightness like quartz on the surface. As a bonus, the cuprite is perched in a small concave pocket lined with velvety powder blue chrysocolla.