Enhancement of gems
Processes which alter the appearance of a gemstone are known in the jewlers' trade as enhancements. While some treatments, such as irradiation, are strictly modern many enhancements of gemstones date back to ancient times.
- cutting & polishing (not strictly an enhancement in the traditional sense, but will be considered here none-the-less)
- dyeing (see also the entry on agate)
- heat treating
- improved heat treating