A knob, nearly a floater with just a tiny contact on the bottom, of dioptase crystals from the prime worldwide locality for the species, Tsumeb. These crystals do not have the clean, green, glassy surfaces you want most in a dioptase, admittedly - natural internal fracturing and complex micro-terracing on the faces gives them a mottled appearance. However, the crystals are large, to one centimeter along the edge, so this is still a significant cluster.