Chalcedony

Pronounced: kal - SED - onny
Chalcedony takes its name from the ancient Greek town Chalkedon, in Asia Minor, which is now the Kadıköy district of Istanbul.
Chalcedony is formed from silica-based minerals. It has a waxy finish, and ranges from white, to gray, to milky blue and almost black. Specific colors are given their own names. For example Carnelian are Chrysophrase are both gemstone varieties of chalcedony. Where the name "chalcedony" appears on a gemstone description, it is almost certainly dyed. The milky varieties of chalcedony take on vibrant colors very well when dyed, and jewelry makers love it for eye-popping creations. However, don't store your chalcedony in sunlight, as it can fade over time.