July Birthstone – Ruby

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Ruby fact file
Crystal Structure: hexagonal
Chemical Composition: corundum – aluminum oxide (Al2O3)
Hardness: 9 MOHS
Refractive Index: 1.762 to 1.77
Colors: shades of red, orange- red, or purple red

Ruby is the July birthstone. This red colored corundum was considered to have many magical powers.

Ruby sometimes displays a three-ray, six-point star. This effect, called asterism, is caused by light reflecting off tiny rutile needles, called “silk,” which are oriented along the crystal faces.Fine rubies are probably among the world’s rarest gems


Ruby took its name from rubrum, which is Latin for red.

Physical and Chemical Properties

Chemical composition

Rubies are a variety of the mineral corundum, aluminum oxide (Al2O3). Ruby and its companion sapphire, are very hard—9 on Mohs scale of 10. Only diamonds and a few manufactured abrasives such as boron carbide and silicon carbide are harder. Rubies are fairly dense—the specific gravity ranges from 3.95 to 4.10 but mostly is almost exactly 4.00. Since ruby crystallizes in the hexagonal system it has two refractive indexes. These range from the extraordinary ray (the one that varies) of 1.762 on the low end to the ordinary ray (the one that remains fixed) of 1.770 on the high end. Ruby is said to be uniaxial negative. Rubies may be dichroic


Color is the most important character of a ruby when it comes to a jeweler properly representing the stone. All rubies must be shades of red, orange- red, or purple red. There is no such thing as a pink ruby. By definition pink corundum is a sapphire. Rubies can vary in hue from brilliant red to violet or brownish red. Any non-red variety of corundum is considered sapphire.

Healing Properties and Interesting Information


A sign of passion and virility, ruby has the power to stimulate sexual desire. It helps to cure peptic ulcer, fever, rheumatism, gout etc.

Where Found

Rubies come from alluvial sources such as Sri Lanka and Burma. Myanmar (formerly Burma) is the source for the most prized rubies – those with the deep “pigeon blood” color. However, Thailand is now the primary world source for the gemstone. Sri Lanka, Vietnam, and Tanzania also have important deposits of rubies, and Australia, Pakistan, Russia, Norway, and the United States (North Carolina and Montana) are secondary sources.

History, mythology

The ancient lapidaries spend considerable time with ruby. “Those be rubies, fairy favors:” a line from Shakespeare’s Midsummer Night’s Dream Shakespeare mentioned rubies several times in his various writings Until improvements in chemical testing in the 1800s, most red gem-quality stones were called rubies. Many of the famous “rubies” in the crown jewels of Europe have since been identified as red spinels or garnets. Large rubies are incredibly rare and can cost more than diamonds. In the thirteenth century, traveler Marco Polo wrote that Kublai Kahn, the Mongol Emperor of China, once offered an entire city for a ruby the size of a man’s finger.A luminous stone, a ruby once supposedly lit an entire chamber in a Chinese palace. Historically, rubies were thought to bestow wisdom, health, luck in gambling, and success with the opposite sex. In the Middle Ages, it was believed that a ruby could warn its owner of misfortunes by deepening in color.

Buying and Caring tips

Tips for Buying Ruby Jewelry

For a one-carat stone of average-to-good quality you can expect to pay between $250 and $10,000 per carat. Of course, truly fine gems will cost more. There are not many stones that can be confused with this july birthstone (spinel has a much lower RI and tourmaline is strongly doubly refractive). In earlier times all of the synthetic rubies were made by the flame fusion process where powdered aluminum was passed through a very hot gas flame. The Aluminum melted and combined with Oxygen to produce synthetic corundum. These stones all had curved growth lines, gas bubbles and flecks of aluminum powder in them. They were easy to spot. There are some synthetic (now called created) rubies that are grown in bombs or crucibles of various kinds that are much more difficult to detect. Diffusion treatment may impart a red to colorless or pale corundum. KashanTM rubies are a flame grown form. DourosTM synthetic rubies are produced in Greece.

Tips to take care of Ruby Jewelry

Clean with soapy water or commercial solvent and brush. Mechanical cleaners are safe, except for heavily included gems.

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