Perhaps no gemstone has been as prized throughout history as the ruby. Celebrated in the Bible and in ancient Sanskrit writings as the most precious of all gemstones, rubies have adorned emperors and kings and inspired countless legends and myths with their rich, fiery hues.

As the ultimate red gemstone, rubies have symbolized passion and romance for centuries. Ruby is the birthstone for July and is also the recommended gem for couples celebrating their 15th and 40th wedding anniversaries.

Also the color of blood, the stone is symbolic of courage and bravery. Warriors were said to have implanted rubies under their skin to bring them valor in battle and make them invincible. The stone has also been used as a talisman against danger, disaster, to stop bleeding, and a number of other ailments. Its intense color was thought to come from an undying flame inside the stone - or, as some legends would have it, a piece of the planet Mars.

Ruby is the red variety of corundum, a sister of sapphire. Like sapphire, ruby rates a "9" on the Mohs scale of hardness, making it the second hardest material known after diamonds.

The most valuable rubies come from Myanmar (formerly Burma), but they are mined throughout Southeast Asia. Good quality stones come from Thailand, Sri Lanka, and Vietnam. Kenya and Tanzania also are becoming more important as

mining sources for ruby. But while the color of the stones from East Africa rivals the world's best rubies, most of these stones are fraught with inclusions that diminish their transparency and value. However, the East African stones are displayed to full advantage in cabochon cuts and have done well in the mass jewelry market. Meanwhile, Afghanistan, Pakistan and Russia have all produced occasional top-quality rubies, but the rough terrain in these areas has made mining difficult.

The most important factor to consider when buying a ruby is its color. It comes in a variety of shades ranging frompurplish- and bluish-red to orange-red. Like sapphire, there is also a translucent variety of