Chalcedony

Chalcedonies are microcrystallised quartz (translucent but not transparent like rock crystal or amethyst) with no zonation (like agate, for example).

The term chalcedony refers to this family, but also to the blue version of this gem. When we want to talk about another colour, we use their specific name.

• chalcedony: blue
• carnelian: red-orange
• chrysoprase: green
• sardony: brown
• onyx: black