Chalcedony is cryptocrystalline quartz with a wax-like lustre which occurs in almost any colour of the rainbow. Should be protected from scratches, sharp blows, harsh chemicals and extreme temperatures.
The Romans prized chalcedony carved into seals, and the Victorians wore finely carved cameos and intaglios. Chalcedony was used in Renaissance magic for health and safety.
Chalcedony is found in many parts of the world, but the most prized Chalcedony are from India, Madagascar, Burma, Brazil, Mexico & USA.