ROCK TRIVIA: CHALCEDONY
Chalcedony probably was named for the ancient Greek town Chalkedon in Asia Minor, which is today part of Istanbul.
Chalcedony was used in the Mediterranean region as early as the Bronze Age. In the Palace of Knossos on Crete, Chalcedony seals have been found dating back to 1800 BC. Hot wax would not stick to it so it was often used to make seal impressions. It was widely used for rings and carvings by the Romans, for religious carvings in the Renaissance and for cameos by the Victorians.
Chalcedony occurs in the most amazing variety of colors and patterns. Agates have beautiful bands and stripes, Jaspers have incredible patterns and colors, and colors range from the translucent orange-red of carnelian to the apple-green of Chrysoprase - the most valued form of Chalcedony.
Generally what jewelers today mean by Chalcedony is the translucent material such as the blue in the picture. Other popular colors are mid-range greens and aquas.