What gives gemstones colors, or rather ... Amethyst, a type of quartz, owes its captivating purple hue to the presence of ...

Chalcedonies include many types of cryptocrystalline quartz gems and feature a number of different colors. Geologists can tell a chalcedony from the arrangement and structure of its crystals.

This gem comes in many different colors, but it is commonly known for ... Citrine is a type of transparent yellow to brownish orange quartz. It is seen as a "success stone" and is associated ...