Emerald is the green variety of the mineral beryl. It is coloured green by tiny amounts of chromium and sometimes vanadium. Aquamarine is another example of the mineral beryl except that it is blue. Other varieties include heliodor (yellow), morganite (pink), bixbite (red) and goshenite (colourless).
Following on from our last blog about emerald treatments, in this piece I will be having a brief look at synthetic emeralds. There are two main methods of producing man made emeralds which are explained below. I have also looked at how these synthetic gemstones can be detected.
A large proportion of emeralds on the market today have been subjected to some kind of treatment process in order to improve their colour or clarity or both. The most common of these treatments is ‘oiling’. This involves filling the cracks in emerald with oil, a process which is carried out under vacuum. The oil is designed to disguise the cracks and to improve the way the stone looks. Whilst most producers of emerald consider this treatment to be normal practice, the oil does tend to dry out over time, leaving behind rather obvious looking pale fractures. Detecting the oil can be difficult. A microscope will often be needed to study any cracks for gaps that the oil has missed. Sometimes flashes of different coloured light will give away the difference in refraction of the oil and the actual emerald.