Specimens of dioptase are often deeply colored and show well developed crystals. The faces of the rhombohedrons, and even the prism faces, are very reflective due to a fairly high luster. Crystals can be quite clear but at times they seem to be cloudy due to the deep color. The special attributes of a high quality specimen of dioptase are hard to describe adequately but must be observed in person in order to appreciate their value. Fine crystals of dioptase are still available in large supplies but their sources are few and the continued demand may put a squeeze on their abundance in the future.
Crystals are transparent to translucent.
The crystal habits include stubby crystals that are usually well formed prisms topped with the three faces of a rhombohedon. Prisms are six sided and usually not very long. Simple rhombohedrons are also common, at times a second rhombohedron will modify the primary rhombohedron faces producing a second set of three smaller faces. Crusts and massive forms are also seen. Cleavage is perfect in three directions forming rhombohedrons.