The Tough Gem: Ruby

Ruby is a species of corundum and ranges in color from orange-red to purple-red. It is medium light to very dark in tone and quite strong in saturation. It is a hexagonal crystal that often comes in six-sided prisms, terminated by flat faces.

Ruby registers a 9 on the hardness scale and is quite tough unlike emerald, and not nearly as subject to breakage. Under long wave ultraviolet, a ruby will fluoresce red or orange-red to inert and under short wave should fluoresce moderate red to orange-red.

Rubies come from a number of areas including Burma, which is usually considered as the finest source of rubies in the world. The best Burma stones are medium dark and vivid red.

Thailand produces stones which are a bit dark in tone and range from purple to brownish red because they have a slight bit of iron in them.  Africa (Kenya, Tanzania) produces stones that are normally highly included although reminiscent of Burma in color. Sri Lanka has occasional rubies but more often sapphires that often mask as rubies.

In the U.S.A., North Carolina and Montana produce a few stones. Australia produces fairly poor quality stones as does India and Colombia, Nepal and Pakistan.

Rubies tend to be valued partially by the country of their origin. Some rubies now come with authenticated certificates of origin and the word Burma will bring a characteristically premium price even when considered next to a Thai ruby that may appear identical to the Burma ruby under incandescent light.

Under fluorescent light, the Burma ruby will appear to fluoresce slightly and take on a deeper saturation. This is a highly sought after quality. Burma rubies also have some fine rutile needles that are commonly referred to as "silk" that add rather than detract to the attractiveness of the stone and further establish it as a Burma stone.

In order to establish a country of origin, a certified lab such as the American Gemological Laboratories in New York, has to study the ruby for body color under various conditions, fluorescence and inclusions. If a ruby is certified as a top Burma ruby, the price may be 1 1/2 or twice what it was as an unknown or as a presumed Thai ruby.

Rubies from Thailand tend to have a brownish or purplish overtone. Those from Sri Lanka are generally very pink in color and more correctly referred to as pink sapphire.