Gemology: C is for ...

Continuing our alphabetical look at gemstones with gemstones beginning with C, our pictorial guide will introduce you to the wonderfully colourful world of ...

Carnelian, Cassiterite, Cat's Eye, Chalcedony, Charoite, Chiastolite, Chlorastrolite, Chrysoberyl, Chrysocolla, Chrysolite, Chrysopal, Chrysoprase, Cinnabar, Citrine, Copal, Coral, Csarite, and Cuprite.

Carnelian / Cornelian A red/amber varient of chalcedony, and one that has been used as a gemstone for thousands of years. It's no longer considered valuable because it's quite common.

Image: 2000 year old jewellery ornament featuring an image of a queen engraved on a large Carnelian, Attribution: © Marie-Lan Nguyen / Wikimedia Commons, via Wikimedia Commons

Cassiterite In gem form Cassiterite is highly desirable, but gem quality minerals are rare. Cassiterite is actually tin ore, and it's the presence of tin that gives jewellery quality gems their fire and brilliance. Cassiterite is a very hard gemstone and usually occurs in brown to black shades.