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

However, emeralds are subjected to a variety of treatments (ranging from highly sophisticated means to backyard experimentations) to enhance their beauty and clarity that eventually improves the look, makes them more saleable and of course fetch a price way higher than they would have before treatment.

What must be categorically understood is that only surface reaching fissures enable success of oiling and therefore degree of clarity enhancement through treatment is directly proportional to surface reaching fissures.

Let us take a look at the various known oiling fillers that are used to give the emeralds a make over:

1. Organic and synthetic oils: As the times have advanced, so has the ingenuity of the treaters—from a time when they experimented with filling emerald cracks and fissures with oils ranging from castor, coconut, cottonwood, mineral, palm, peanut, olive and others to a combination of oil, they have come to understand that they need to choose an oil that has a refractive index similar to the emerald and that the oil must have a fairly high viscosity.

A suitable refractive index allows the oil filler to blend and merge as one without creating visual differences. The crystal has a uniformly constituted look to the eye. High viscosity at room temperature implies that the filler will not thin out and exit easily.

This gives stability to the gem’s appearance. It must be kept in mind that enhancing treatments are transitory in nature and the gem will revert to its original look as the filler decomposes and dissociates over time.

It will then need another round of “oiling” to regain lost glory. Cedarwood oil over the years has emerged as favourite filler for emeralds and is accepted in the gem trade, although disclosure of treatment is a must.

Cedarwood oil has a refractive index of nearly 1.512 and it remains colorless over the years in comparison to ‘palma’ or palm oil, which turns milky white with time. The R.I. of emerald is 1.577 – 1.583 + .002. The gem report detecting this oiling is likely to read E - colorless – oiled.

To be continued...