Emerald
Emerald's rich green color is so striking that almost everyone is entranced by it. The history surrounding these green rocks is a tangled web of legend, superstition, and corruption. Ancient emeralds came mostly from Egypt, and were of poor quality. When the Spanish conquered the Incas, they found many fine emeralds that had been produced in Colombia. The Incas were able to keep the source of the stones a secret until the late seventeenth century when the Spanish finally discovered the Colombian mines. Today, emeralds are being produced in Colombia, Brazil, Zambia and Pakistan. Almost all emeralds have been treated with oils or resins to minimize the optical effect of surface reaching flaws. They have a hardness of 7, but are usually fragile due to the large number of inclusions present. Best suited to earrings, pendants and "special-occasion" rings.
Treatments: Fracture filling of some type is almost universal, typically clear oils, but sometimes epoxy resins.