Gemstone guide
Gemstone Treatments
Common gemstone treatments, what they change, and the importance of disclosure.
Heat
The most common, and the most stable
Standard practice for sapphire and ruby for centuries. Heat deepens color and can clear internal haze. It is permanent and stable — a heated sapphire needs no special care.
Oil and resin
Standard for emerald, and not permanent
Emeralds form with fine surface-reaching fissures, and a colorless oil or resin fills them so they disturb the eye less. Accepted throughout the trade, but not permanent: avoid ultrasonic cleaners, solvents and prolonged heat, and expect an emerald to need re-oiling at some point in its life.
Untreated
Uncommon, and priced for it
A stone that reached its color and clarity unaided. Genuinely uncommon in fine material and priced accordingly.