The Ruby Gemstone in Jewelry and Ball Bearings

The Ruby is a precious gem that has been used in jewelry for centuries. Its molecular structure is made up mainly of aluminum and oxygen (Al2O3). But it is minor amounts of chromium in the structure that give it the red coloration. When there is no aluminum in the stone, the Cr2O3 is called eskolaite and is green. The Ruby has a hardness of 9 on the Mohs Scale. The Ruby is in the class of stones called corundum.

The class of corundum also includes sapphires. Sapphires have largely the same chemical makeup as rubies and differ from rubies only in trace elements, making rubies red sapphires. Rubies are rare gemstones. Large rubies found in nature are even more rare than diamonds and a perfect specimen will usually fetch a higher price than a diamond of comparable size. For a ruby to have value it must also have clarity. Opaque rubies have little value. The most prized rubies are "Blood Rubies" from Burma. But the most common rubies are from Thailand. The ruby is the birthstone for the month of July.

Some rubies have inclusions of Rutile needles which can cause star-like asterisms in the stone. Such a ruby is called a "star ruby". It can have six or, rarely, 12 rays.

Synthetic Rubies

Heat treating a ruby, or putting it under intense heat and pressure, can help to remove flaws and improve the coloration. Rubies may also be created synthetically. Marc A. Gaudin, a French Chemist, was the first to be successful at creating rubies synthetically in the late 1830s. His efforts, however, produced very opaque gems. In 1885 some synthetic gems were made and introduced to the market. The makers did not reveal the source of the gems, making the buyer suspicious. Analysis proved that the rubies were man-made and so became value-less. It seems that they were produced by "melting powdered aluminum oxide and a smaller amount of chromium oxide in an array of torches, and letting the molten material solidify."1

A Ruby Used as a Bearing in a Watch Image

Auguste Verneuil in the late 1890s came up with a process that was more efficient. He produced rubies by flame infusion. He could grow rubies of 12 carats in size in a matter of two hours. At the close of the First World War (Great War), 1918, J. Czochralski created a process called crystal pulling, in which a rod with a "seed crystal" on the end is barely immersed and spun in a heated solution of a nutrient comprised of the necessary elements of aluminum and chromium oxide. These attach themselves to the seed crystal and continue to grow as the rod is raised, "pulling" the crystal from the solution. Using this method, within a few hours, high quality rubies two inches (50mm) thick and 40 inches (one meter) long can be made relatively inexpensively. (An alchemists dream come true.) This process is commonly used in ruby synthesis today.

Most synthetic rubies are used in manufacturing processes. Rubies found in nature are the ones commonly used in jewelry.

The Ruby in Industry

Besides being used in jewelry, rubies are used in lasers because they have exceptional wave-transmitting properties throughout the light-wave spectrum. Because they are second only to diamonds in hardness they are used to guide threaded needles in textile machines and can be used as bearings where friction needs to be reduced in precision devices.

The Ruby in History

Throughout the ancient and medieval periods rubies were prized especially by royalty. They could be found in many a crown and other jewelry. However, at the time they had difficulty distinguishing the difference between rubies and spinel. Rubies are known to have been mined for nearly 10,000 years. Some of the most prominent rubies have come from Afghanistan, including the mines at Jegdalek-Gandamak, which is located near Kabul province. There is a legend that when a ruby turns a deeper red, it signifies danger for the wearer. It is said that Catherine of Aragon predicted her own death by "reading" her ruby.

Other Ruby Notes

"Ruby" is a popular name for children. Its popularity has grown in recent years in English speaking countries, and is derived from the word for the gem2. A simple but elegant programing language has been developed called "Ruby". It was developed by Yukihiro "matz" Matsumoto3 as an object oriented language.

< Sapphires: The September Gemstone | Return to Index >

1. Synthetic Rubies
2. Think Baby Names - Ruby
3. Ruby Programing Language

Interesting Fact:

The one-time King of Burma (now the country of Myanmar) was known as the "Lord of Rubies" because his country produced some of the greatest natural rubies in the world.


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