Which one is the Emerald?

May 23rd, 2009 by James L. Sweaney, CGA, FGA. GG

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The pure grass green color of the Emerald has long been symbolic of serenity and virtue and is the primary reason why emeralds have been treasured and sought after for so many centuries.  The qualities of beautiful color, rarity, and durability (see my blog on restoring damaged Emeralds) have traditionally earned the emerald the reputation of being “precious”, a designation for the upper echelon of gems based on their high value.  While some people still label gems as “precious” and “semi-precious”, this distinction has become obsolete because so many of our new gems are very rare and valuable—witness the enormous sums paid for fine collector stones, like this $100,000 plus Paraiba tourmaline.

Museum Quality 10 ct Paraiba Tourmaline

Museum Quality 10 ct Paraiba Tourmaline

Today, with extensive gem prospecting world wide yielding exciting new finds, we have wonderful gemstones that rival the beauty of the emerald, are equally rare and are similar in their physical durability, but are much more affordable than Emeralds.

My favorite is the Tsavorite Garnet. This rare variety of grossular garnet was discovered by British geologist Campbell Bridges in 1967, while prospecting the area bordering Tanzania and Kenya.  The name is derived from the Tsavo National Park in southern Kenya—some mineralogists and gemologists argue the name “Tsavolite” is more scientifically correct, but the generally accepted gem trade usage is still Tsavorite. Besides having an intense and wonderful rich green color, Tsavorite crystals are generally highly transparent. High clarity coupled with a relatively high refractive index gives the Tsavorite brilliance and sparkle never seen in Emerald. Rare in clean gems over one carat, and extremely rare in stones over 10 carats, fine to extra fine Tsavorites are generally one-third the cost or less than similar quality Emeralds. This extra fine one carat Tsavorite from our Gallery of Gems is priced at $1495—compare with Emeralds costing $5000 plus.

1.02 ct. Tsavorite Garnet

1.02 ct. Tsavorite Garnet

Like the Emerald, Chrome Tourmalines derive their grass green color from trace amounts of chromium. A rare tourmaline from Tanzania, these richly green gems are hard to find, yet even more moderately priced than the Tsavorite—this extra fine (almost) two carat Chrome Tourmaline from our Gallery of Gems is a great value at $1295

1.92 ct Chrome Tourmaline

1.92 ct Chrome Tourmaline

One major plus for both Tsavorite and Chrome Tourmaline is that unlike Emerald, these gems are not treated or enhanced in any way, other than by cutting.  While many Tourmalines are indeed heated to improve color, the Chrome Tourmaline variety is not heated, and no Garnets are treated or enhanced– for complete information about gem treatments, download the free AGTA Gemstone Information Manual.  For those persons who want gems that are as natural as possible, these two gems are excellent choices.

A few transparent green gems have color similar to emeralds but none have the properties of durability required for a wearable gemstone. For example, Chrome Diopside, the darling of TV shopping networks, is beautifully green but it’s hardness is only 5 – 6 meaning it can be easily scratched.  Also, it’s crystal structure allows good cleavage planes, meaning it can crack or split if struck along the direction of cleavage.

So, which is the Emerald?  If you guessed the center stone, go to the head of the class. It’s slightly bluish medium green color is just right. This beautifully cut 1.31 ct. Brazilian gem is so unusually clean and transparent that it dances in the light and is sure to bring the comment “Is that real? I didn’t know Emeralds were so sparkly!”  A bargain at $5495, you can see its full grading report at our Gallery of Gems

1.31 ct Emerald

1.31 ct Emerald

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