Emerald - the symbol of rebirth and bringer of good fortune and youth - is the birthstone for those born in May.
A variety of green beryl, the name emerald is derived from the Greek word smaragdus (green in Greek). The green colour of emerald is caused by traces of chromium, but vanadium may also be present in some stones.
Read more: Aquamarine for Those Born in March
Emeralds can be found in Colombia. Brazil, India, Pakistan, Siberia, South Africa, Zambia and Zimbabwe.
The inclusions contained in almost all natural emeralds are very useful in distinguishing natural emeralds from synthetic emeralds and other green stones. Some inclusions are common for particular localities.
|Locality||Typical Inclusion and Features|
|Colombia||Three-phase inclusions (liquid-filled cavity containing a crystal and a gas bubble)|
|India||Two-phase inclusions (liquid-filled cavity containign a gas bubble)|
|Zimbabwe||Tremolite (usually fibrous or neddle-like crystals)|
|Siberia||Needle-like crystals of actinolite|
|Many Localities||Mica flakes, pyrite and calcite, and also colour zoning|
Combining the typical inclusions found with an assessment of refractive index and specific gravity can give an indication of the country of origin. ■
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Cover image needle-like inclusions in emerald. Image courtesy of Pat Daly.
Featured in the Spring 2018 issue of Gems&Jewellery, Rui Galopim de Carvalho FGA DGA explores how ‘alternative facts’ have resulted in an informal nomenclature that permeates the world of gemmology. Here, he offers some examples of these long-standing quirks in terminology.
From the the Spring 2018 issue of Gems&Jewellery, here Harold Killingback FGA explores chatoyancy in sillimanite cabochons, an optical phenomenon where a band of light, known as a 'cat's eye', appears to hover above the surface of a stone, resulting in a striking lustre and colour.
Every year Gem-A gives its members and students the chance to show off their skills with the camera through the Gemstone Photographer of the Year competition. Have you got what it takes to be Gem-A's best photographer of 2018? Entries are open now and close on August 31, 2018.