Birthstone Guide: Emeralds for Those Born in May

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.

Emerald with quartz. From the Gem-A archive.
Emerald with quartz. From the Gem-A archive.

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

 

Three-phase inclusion. Image courtesy of Pat Daly.
Three-phase inclusion. Image courtesy of Pat Daly.

 

Two-phase inclusion. Image courtesy of Pat Daly.
Two-phase inclusion. Image courtesy of Pat Daly.

 

Needle-like inclusion. Image courtesy of Pat Daly.
Needle-like inclusion. Image courtesy of Pat Daly.

 

Pyrite inclusion. Image courtesy of Pat Daly.
Pyrite inclusion. Image courtesy of Pat Daly.

 

Mica inclusion. Image courtesy of Pat Daly.
Mica inclusion. Image courtesy of Pat Daly.

 

Crystal inclusion. Image courtesy of Pat Daly.
Crystal inclusion. Image courtesy of Pat Daly.

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. 


Understanding Dioptase

Understanding Dioptase

Did you think this might be emerald? You certainly wouldn't be the first to confuse the vibrant green of dioptase with the more recognisable, jewellery-lover's gemstone. Here, Gem-A assistant gemmology tutor, Dr Juliette Hibou FGA, explains more about the history, properties and origins of dioptase, an unusual collector's gem. 

Read more