Ruby: The King Of Gems
“A woman of valor, who can find? For her price is far above rubies.” –Proverbs 31:10
Ruby, the birthstone for July, is called “the king of gems” for its position as one of the most important gemstones in the jewelry world. Among colored gems, rubies can command the highest price per carat (a 25.59-carat ruby sold at auction for $1.2 million per carat in 2015). And as we see from the Biblical quote above, they’ve been prized since ancient times.
Ruby is the gemological twin of sapphire. Both are the exact same mineral, corundum, but different trace elements within the mineral create different colors. Red is caused by the presence of chromium, and only deep red corundum may be called ruby. Any other color of corundum is called sapphire, which occur in every color under the sun. We’ll talk more about sapphires in a later post. In addition to its designation as the only birthstone for July, ruby also is the traditional gift for a 40th wedding anniversary and, more recently, the 15th anniversary as well.
The value of a ruby is predominantly determined by its color. The most rare, and therefore most valuable, are bright red, sometimes called “pigeon’s blood.” A ruby displaying this color will command a much higher price than a stone of similar clarity and size that lacks the color intensity. Ruby’s red is a cool red, as compared to a garnet, which tends to be a warmer or brownish red. Rubies are quite hard—9 on the Mohs hardness scale, compared to diamond’s 10—so they’re highly scratch resistant.
After color, clarity is the next determinant of value in a ruby. Like diamonds, the greater clarity of the gem, the higher the value. If you recall from our diamond discussion, minute flaws in a stone’s clarity are called inclusions. But in a ruby, certain inclusions are desirable, namely those that show a star or cat’s eye pattern. These effects occur when light is reflected off precisely oriented rutile needle inclusions in just a certain way. Star rubies can have three or six points, depending on the rutile pattern, while a single ray down the center gives the cat’s eye effect. Stones that display either of these effects are cut as cabochons (smooth, round top) to show off the effect at its best. Rubies and sapphires also can show a color-change effect, though this is extremely rare.
Rubies are found predominantly in Southeast Asia and eastern Africa. The most valuable rubies came from the Mogok area of Burma (now Myanmar). Highly prized for their rich “pigeon’s blood” color, they’re even more valuable today for two reasons: one, very few top quality rubies have been found in that area in recent years, suggesting the deposit may be close to tapped out; and two, the United States has banned the import of both rubies and jadeite from Burma/Myanmar due to human rights issues. Other areas of Myanmar—such as Mong Hsu in the central region of the country—remain key ruby-producing areas, but the stones can’t be sold in the United States.
That’s not to say jewelers like myself can’t sell fine Burmese rubies. We can, just with certain provisions. Antique Burmese rubies, as well as those already in the United States, are legal to be sold here, but when jewelers travel with ruby outside the United States, we must provide adequate proof of the stone’s age and origin to bring it back in.
Other sources of ruby include Thailand, Vietnam, Cambodia, Madagascar, Brazil, and several African nations, especially Kenya and Mozambique. Sri Lanka also has a significant deposit of lighter pink rubies, often called “pink sapphire.” While attractive in their own right, their color is not a deep enough red to be considered ruby.
A fairly significant deposit of ruby—along with diamonds and other gems—was discovered in Greenland in the latter part of the 20th century, but to date has not been mined commercially.