Emerald is the best known and most valuable variety of the mineral beryl, with a characteristic deep green color. It is due to the chromium content in the structure. In jewelry, it is used as a precious stone (faceted cuts, cabochons). The most famous jewelry with emeralds include the Necklace of the Spanish Inquisition, Hooker's emerald brooch or the Andean royal crown. Emerald (smaragdos) was first used in ancient Egypt, it was one of the favorite stones in the Middle Kingdom, during the Ptolemaic period and under Queen Cleopatra. More info