Latest Findings
Posted by aloysiushan on July 31 2009 11:03:41
Some latest findings from around the world:
New outcrops of
- Colour change garnets discovered in Kenya rivalling the best in Madagascar in the best qualities. Sizes are largely limited to below 3 carats, the majority are sub-caraters. Gem quality materials are confined to the smaller sizes.
- Chinese rhodochosite. Gem quality/facetable grade rhodochrosite has been discovered in China. Perhaps a new take on the classic Sweet Home Mine?
- New Russian Demantoids with classic horse-tails. A new mine has started producing russian demantoids with the highly desired horse-tail inclusions.
AGTA has decided to scale some operations due to the financial crisis related lack of demand for its services. Dr Lore Kiefert, of the andesine misidentification fame, will be moving to Gubelin Gem Lab to be chief gemmologist.
Demantoids can be heat treated
Laboratory Approaches Towards Disclosure
In the beginning the labs would not make the heat-or-no-heat call because it was undetectable. As their databases grew and internal characteristics began revealing more clues, new assumptions were made. Below are some of the current approaches the major laboratories are taking.
- Gemological Institute of America (GIA) – Will not identify whether a demantoid garnet has been heat treated; will not determine origin on demantoid garnets
- American Gem Trade Association (AGTA) disclosure – Enhancements: Indications of heating. Gemstones of this type may be heated to improve their appearance. This treatment is not detectable using current technologies; such heating is generally stable under normal wearing conditions. AGTA is not giving country of origin
- American Gemological Laboratories (AGL) disclosure – AGL will make the heating call, and give country of origin
- “It is in the opinion of the Laboratory, based on the weight of evidence, that the origin of this material would be classified as Russian. It is the opinion of the Laboratory that this material has been subjected to a low to moderate heat enhancement process to produce a permanent and stable color.”
- Gübelin Gemmological Laboratories – Will denote the country of origin but not whether the material has been subjected to heat
- SSEF Swiss Gemmological Institute – Will state country of origin and whether there are indications of heat treatment
The labs that do report country of origin are not able to pinpoint specific mines at this time.