Glossary term
Geuda
Milky, desaturated corundum that can turn fine blue when heated.
Geuda is a Sri Lankan trade term for translucent, milky or desaturated corundum that shows little beauty in its natural state but can develop transparent, saturated blue colour on high-temperature heating. Once considered near-worthless, geuda became commercially important with the development of modern heat treatment. Heated stones must be disclosed as heated.