Gemstone Glossary

Shiller effect - any observable event which results from the interaction of light and matter. i.e. When you tilt some gemstones back and forth you are able to see a different colour.

Siliceous rocks - sedimentary rocks that have silica as the principal constituent.

Drusy - Covered with a large number of minute crystals

Cryptocrystalline - Having a microscopic crystalline structure.

Dentritic - A mineral crystallizing in another mineral in the form of a branching or treelike mark.