Natural Emerald—The Gemstone
of Communicative Mercury continues....

Canada balsam is yet another preferred filler. Canada balsam cannot exactly be categorized as oil, but rather as an oleoresin. Canada balsam is generally considered a natural resin and is used to seal the Cedarwood oil.

Canada balsam has a refractive index of 1.520. The gem report detecting this oiling is likely to read E - colorless – oiled.

3. Of late, epoxy resins (polymers used as adhesives) have started replacing oils.

The most popular is a synthetic polyester epoxy resin, going by the trade-name “Opticon”, notoriously effective as a fracture sealer that has found favour because it is more stable than oil. Opticon is transparent and comparable in viscosity to that of Canada balsam. It has refractive index of about 1.545. Sometimes hardeners may be added to the polymer but they are generally avoided as it would pose a problem when re-oiling of the emerald is required. There have been instances now where coloured Opticon (mixed with green organic dyes) is now being used on emeralds as well.

4. Gematrat and ExCel: The Arthur Groom, New York brought out two products for enhancement of emeralds – Gematrat a product, essentially an improvement on Opticon – an enhancement that will not turn yellow.

The other enhancement is called ExCel. It also goes by the nickname “1.52” in a bid to get it acceptability like Cedarwood that has the same RI. The gem report detecting this oiling is likely to read E-Colorless- Resined.

5. Joban: This is the Joban oil treatment that is used by the emerald traders in India. The green oil dyes the gem. Even colourless beryl can be changed into a fine green emerald using this treatment. The gem report detecting this oiling is likely to read T – Dyed.

6. Permasafe: This is one of the most advanced filler for emeralds. The Permasafe Lab, Bogota provides an option for permanent enhancement. Permasafe does not color treat the emeralds. The gem report detecting
this oiling is likely to read E-Colorless- Resined.
T – Treated; E – Enhanced.

To be continued...