Description Black chalcedony onyx slab (Africa) orders will contain at least five one inch squares for one order. Slabs are available from one order to possibly 3 or 4 orders per slab, and four orders could give you a slab with 20 one inch squares in the slab. This semi-precious gemstone is a popular and classic color for jewelry and will take a nice polish. Another use for black chalcedony onyx is as a base to apply opal to, and this will brighten the colors of the opal. Clear quartz is then applied to the top of the opal cabochon to protect the soft opal. Stock 403s
