Diamonds and oils of refraction?

Question

One way to test the authenticity of a diamond is to submerge it in a specific oil, where it will 'disappear' because of the diamond's and oil's index of refraction.

Does anyone know the name of this oil used to test diamonds and/or it's chemical formula?

Thanks

Answer 1

Diamond has an extremely low thermal expansion, is chemically inert with respect to most acids and alkalis, is transparent from the far infrared through the deep ultraviolet, and is one of only a few materials with a negative work function (electron affinity). One consequence of the negative electron affinity is that diamonds repel water, but readily accept hydrocarbons such as wax or grease.
http://chemistry.about.com/cs/geochemistry/a/aa071801a.htm?terms=gemstone+jewellery this site is the closest that I could get to finding a specific formula. I do not think that there is a formula. I am guessing that diamonds are accepting to most greases and oils.

I gave you this to read on I found it interesting if you want to learn more about diamonds.
http://www.livescience.com/technology/050516_diamonds.html

Answer 2

Sorry but the immersion in highly refractive liquids (which is a very crude method of measuring R.I. any way) is not a method that works for diamond. The reason for this is that the R.I. of diamond (2.42) is far too high for the normal liquids used in gemmology and also there are no other chemicals that you can use. It is also worth noting that all the liquids used for R.I. testing in the upper ranges are poison and give off dangerous vapour, many also burn the shin. As a result they can only be used safely in a laboratory.
Diamond has more than enough unique characteristics to make its identification easy and you can look these up in any good book on gemmology. "Gem Testing" by B.W. Anderson is very good. It is published by Butterworth & Co.

Answer 3

An easier way to test something you may find as a diamond would be to test it's thermal conductivity. A diamond has high thermal conductivity and will feel cool to the touch in comparison to a plastic or glass imitator. (Other gems that imitate diamonds will have some level of thermal conductivity but the only way to distinguish those is to use a thermal tester).