Also like agate, onyx is easy to dye. The recipe calls for boiling the stone in a sugar solution, then letting it steep in sulphuric acid. When the acid hits the sugar, black carbon is created, which seeps into the stone. This technique is used a lot because the demand for black onyx far outstrips the supply. In fact, dyed black onyx was used liberally during the Art Deco era, when dramatic contrasts and hard edges were all the rage.


Green Onyx Art Deco/Nouveau Necklace
A bracelet present to my mother in ?…









