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Gem of the Month: Emerald

Posted May 2, 2006 By AussieSapphire

emerald1.jpgThe gemstone for May is Emerald, also known as the Gemstone for Spring for its beautiful colour. In fact, relatively clean gems of intense grass-green colour are among the most valuable of all gemstones.

Gemmology Matters: Emerald is the green variety of Beryl – a mineral with the composition Be3Al2(SiO3)6. Emeralds are found in many countries with Columbia recognised as the source of the finest gems – emeralds are also found in Brazil, Pakistan, Russia, Australia, Africa, India, Norway, and the United States.

Emeralds have been commercially mined in Australia in only two main areas: the New England region (Emmaville and Torrington) and in Western Australia near the Poona district. Emeralds were first mined near Emmaville in the early part of the 20th Century with over 53,000 carats produced over 20 years of intermittent production. emeraldxtl.jpgAnother attempt at commercial mining took place at nearby Torrington in the early 1990’s – while the gems were of good quality, it appears the source is now exhausted. The photo at left shows an excellent example of an New England emerald (courtesy GAA – see link below).

The difference between green beryl and true emerald is determined by chemical analysis with emerald containing traces of Chromium Oxide. Where chromium is not present, the colour of green beryl is caused by traces of vanadium and/or iron. There seems to be some discussion among experts about what percentage of chromium compared to vanadium is required to qualify as emerald. Given that gems of a range of colour intensity are found in both Cr-coloured and Va-coloured stones, I suggest the point is somewhat moot and people should choose a colour that appeals to them. In practice, the name emerald is usually reserved for the gems of better colour (intense grass green of pure tone) with those of lighter colour (and perhaps yellowish tone) are referred to as green beryl.

Although emerald has a hardness of 7.5 to 8 on the Moh scale, it is usually regarded as quite a brittle gem due to the high level of inclusions typically found in these stones. Emeralds usually contain many cracks, fissures, and inclusions – for this reason, most emerald are “oiled”, an enhancement treatment which immerses the stone in oil in order to reduce the visibility of the inclusions and improve clarity. Because this treatment is almost universal, it is usually not disclosed to buyers. Emeralds should be treated with particular care and never cleaned in an ultrasonic or steam cleaner as this may damage the stone or may cause the gem to require “re-oiling”.

chatham_emerald.jpgSynthetic emeralds have been widely available for some decades and will display excellent colour and clarity.  While easily distinguished from natural emeralds with their typically included appearance, microscopic inspection of stones may be necessary to distinguish synthetic emerald from very high quality clean natural emerald.  The example at left is a Chatham emerald (see www.chatham.com for more information).

Mythology and Lore: The name emerald is thought to derive from the Ancient Greek word “smaragdos” meaning green stone and was originally applied to a variety of green colored minerals. Emerald is the birthstone for May as reflected in this old English nursery rhyme:

“Who first beholds the light of day
In spring’s sweet flowery month of May,
And wears a Emerald all her life,
Shall be a loved, and happy wife.”

Emerald is often given as an anniversary gift for the 20th and 35th anniversaries or as an alternate stone for the 55th wedding anniversary. Emerald have been long been associated with eyesight – it has been used to cure diseases of the eye and enhance clairvoyance. It is said that Nero used an eyeglass made of transparent emerald to improve his vision while watching the gladiators in the arena. Emeralds were also used as amulets to ward off epilepsy in children and were thought to improve memory, intelligence, and enhance love and contentment. Legend holds that if an emerald is given by one sweetheart to another, it will pale and grow dull when the love between them fades.

Emeralds have been highly prized by many cultures for thousands of years. Known to have been sold in the ancient market of Babylon over 4000 years ago, they feature in many legends and myths. In Greek mythology, Hermes composed a tablet carved from a giant emerald as a gift for Aphrodite. In the Book of Revelations, the throne of God is said to be made from emerald and the Holy Grail carved from a huge emerald which fell from Satan’s crown upon his banishment from Heaven. In Hebrew lore, emeralds were one of the four precious stones given to Solomon.

Cleopatra prized emeralds above all other gems – the famed emerald mines of Egypt from over 2000 years ago were near the Red Sea and owned by Cleopatra. The Moguls of India, including Shah Jahan, builder of the Taj Mahal, admired emeralds so much they inscribed them with sacred text and wore them as talismans. The incredible beauty and quality of the fine emeralds found in South America enflamed the greed of the Spanish Conquistadors arriving in South America. Pissarro, the leader of the Spanish, ordered that Incan rulers were to be tortured until they revealed the location of the emerald mine. In 1557 the Spanish finally found the fabulous Muzo mine in what is now Colombia – an important source of fine emerald to this day.

Alternatives in Green: Green symbolises the element earth and represents fertility, prosperity, employment, money, healing, and growth. While emerald is perhaps the most valuable of all the green gems, there are alternatives to suit every budget. For everyday wear, green sapphire is an excellent choice with a hardness of 8 – good quality greens are very rare but often priced quite reasonably compared to other sapphire colours. Green sapphire may be less brilliant than some of the other alternatives and can have a slightly olive tone. Demantoid and Tsavorite Garnet are both very bright green gemstones with good brilliance and intense colour. Peridot is an affordable alternative to emerald and in fact is sometimes misleadingly called “Evening Emerald” although usually the colour is slightly yellowish compared to the pure green of quality emerald. Tourmaline can come in beautiful shades of green – often with some blue tone – some varieties are highly sought after. Opaque alternatives in green include jade and chrysoprase.

Links of Interest:

Emerald Factsheet at Mineral Miners
Wikipedia article on Emerald
ICGA Gem-by-Gem article on Emerald
Bernadine Fine Arts Jewelry – Emerald article
GAA Gem Gallery – Australia’s Emerald Deposits
The Emerald Deposits of Muzo, Colombia (reprinted by Palagems)

We currently have a small amount of green beryl in stock – some originates from Nigeria but some is from our own backyard (the Emmaville/Torrington area). Most of this is of the lighter green colour typical of these sources but some very attractive crystals here along with some interesting facet rough.

cheers for now from Andrew and Leah (Aussie Sapphire)