Ruby

Ruby is a variety of the mineral species corundum and has been a popular gemstone for centuries. It has picked up many legends along the way.

People in India believed that rubies enabled their owners to live in peace with their enemies. In Burma (a ruby source since at least 600 AD — now called Myanmar), warriors wore rubies to make themselves invincible in battle, Rubies were worn in medieval Europe to guarantee health, wealth, wisdom, and success in love. As the US birthstone for July, ruby still captivates the hearts and imaginations of gem professionals and consumers alike.

Large, fine-quality rubies are extremely rare and valuable. But strong worldwide production and an array of treatments have increased availability and put rubies within the reach of most customers.

Common cutting styles for ruby include mixed-cut ovals or antique cushions for transparent material, and cabochons or beads for translucent to opaque stones. Corundum has excellent toughness, and it's harder than any other natural gem except diamond. This makes it ideal for rings as well as many other types of jewelry.

The name ruby comes from the Latin word ruber, which means "red." The most expensive ruby color is a deep, pure, vivid red. Stones a little pinkish, purplish, or orangey red are also considered rubies, but gem and jewelry professionals make careful distinctions between ruby and pink, purple, or orange sapphire. (Ruby and sapphire are both corundum varieties.)

Generally, the difference depends on a combination of hue, tone, and saturation, but market culture and geography also make a difference. Gems that would be considered pink or purple sapphire in the US may be classified and sold as rubies in some Asian countries.

Major Sources
Afghanistan, Kenya, Madagascar, Myanmar (Burma), Sri Lanka, Tanzania, Thailand, Vietnam.

Hardness & Toughness
Ruby has a hardness of 9 on the mohs scale, and usually has excellent toughness. Stones with certain treatments or large fractures or inclusions may be less durable.

Stability
Heat can cause a change in color or clarity, it can also damage or destroy fracture- and cavity-fillings. Rubies are generally stable to light, but bright lights can cause oil to leak or dry out. Chemicals can harm fillings and remove oil; soldering flux containing boron and firecoat made with boric acid powder, will etch the surface of even untreated stones.

Treatments

* If there is any doubt, send the gem to a gemological laboratory for verification.

Care and Cleaning
Rubies can be cleaned in warm, soapy water, but avoid strong detergents and vigorous scrubbing on oiled stones. Ultrasonic cleaning and steam cleaning are usually safe, but never for fracture- or cavity-filled stones.

Imitations
Glass

Synthetics
Czochralski
Flame fusion
Floating zone
Flux
Hydrothermal

Text from GIA's Essential Colored Stone Reference Guide