GEMSTONE TREATMENTS INFORMATION

Coloured stones are often subjected to various treatments to improve their appearance. Treatments are considered usual and customary practices when properly disclosed and when done without intent to defraud the consumer. Many treatments are stable and do not require special care. Others may require special care. When a treatment is detected and considered not to be usual and customary it will be so noted by this appraiser. Some treatments are reversible and re-treatable. It may be beyond the scope of an appraisal to determine exact treatment methods or the amount of treatment present. Some treatments require sophisticated equipment to identify, not found in a standard gemological laboratory.

All treatments should be disclosed to the purchaser. Market values are generally based on these treatments. Unless otherwise stated, the coloured stones for sale are assumed to have been subjected to one or more of these treatments, when it is common for that species or variety, and valued accordingly. Treatments, when detected will be noted on the appraisal. Untreated gemstones, when detected and when the value is affected, will be noted. Unstable treatments or other treatments that adversely affect the value will also be noted in the appraisal when detected.

The following list describes some common gemstone treatments. It is not inclusive of all treatments.

Gemstone Treatment Frequency Stability Care of Gem
Ruby Heat, poss. residue Usually Excellent Normal
Sapphire Heat Usually Excellent Normal
Emerald Oil, opticon or other Usually Fair to good Caution
polymer resins
Tanzanite Heat Always Excellent Caution
Pearl Bleach Usually Very good Caution
Opal Oil, wax, epoxy Rare Fair Caution
Blue Topaz Irradiated Always Excellent Normal
Other gemstone treatments include irradiation, dye, various coatings, and diffusion. Some treatments such as dye may be considered fraudulent if not properly disclosed.