Rubies are one of two varieties of the mineral corundum, the other variety being sapphires. The ruby is July’s birthstone and ranges in color from pink to “pigeon blood red,” which is the most valuable.
Like sapphires, rubies are the second-hardest natural mineral in the world, coming in behind diamonds. All natural stones contain imperfections, such as rutile needle inclusions (called “silk”), and color impurities. Jewelers and gemologists can use the silk to determine whether it is genuine or synthetic. Most available today have been heat-treated to offset naturally-occurring cracks and other inclusions caused by chrome during these stones’ formative years within the Earth’s core. Yet if chrome had not been present, these stones would not have received their beautiful color.
Rubies with silk that shows a three- or six-point asterism can be cabochon cut to provide a star-shaped effect. When this effect is present, the silk actually increases the value of the stone. Star varieties are extremely rare and should be transparent.
Natural stones rarely contain pure hues, so primary, secondary, and occasionally tertiary hues are referred to in connection with colored gemstones. “Pigeon blood red” (also described as “a vivid medium-dark toned red”) should be the primary hue. Typical secondary hues include pink, orange, and purple. Of these three, purple is preferable because it reinforces the red, giving it a richer appearance, and it occurs halfway between red and blue on the color wheel. If this type is set in yellow gold, the yellow will neutralize the blue in the stone, causing it to appear pure red.
While garnets and red spinels can greatly resemble the ruby, a genuine one is much harder than these substitutes. In fact, many famous stones previously thought to be rubies have later been discovered to be garnets or spinels. When you purchase a genuine stone, it is important to get a certificate, especially if it is expensive. And if you purchase your gem over the Internet, make sure you’re dealing with a reputable jeweler.
Because of their vibrant color, these stones have long been associated with passion and love, and they are a popular Valentine’s Day gift. Whether you prefer a pendant, earrings, or a ring, Jeweler.com can help you choose a stone you’ll be proud to own.