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Roger Weller, geology instructor                     

Michael Schweska
Physical Geology
Spring 2005

                                              July Birthstone-Ruby

Ruby is the official birthstone for July as adopted by the American National Association of Jewelers in 1912. It is also the birth stone for the Zodiac sign of Cancer. Ruby is suggested as a gem to give on the 15th and 40th year wedding anniversaries. Ruby is 9.0 on the Mohs scale of hardness. If you own Rubies, it is good to remember that hardness and susceptibility to breakage are not necessarily related. Even though exceedingly hard, heavily included stones may crack or chip when hit. The main sources of Ruby are Thailand, India, Madagascar, Zimbabwe, North Carolina in the U.S., Afghanistan, Pakistan, Sri Lanka, Kenya, Tanzania, Kampuchea, and perhaps most notably, Burma. Ruby's day is Tuesday, its season summer, and its apostle St. Matthew. Rubies are more than talismans or good-luck charms, not only historic and exotic but also valuable. Value is a human set of conditions: gems must have rarity, durability and beauty. Great rubies display all three hallmarks. Rubies - especially fine rubies - are rarer than diamonds, emeralds or sapphires. Ruby

Some of the famous rubies recorded were a 98- and 74-carat pair, a 400-carat rough that was later cut to produce a 70-carat finished jewel, a 45-carat gem said to have sold in Mandalay and a 20-carat jewel sold in Calcutta. Click here for a picture in natural form. Click here for more faceted and natural specimens.


Color is everything with rubies. How much red can you afford? The richer, deeper, better the red, the more expensive and rarer the ruby. Fine rubies are the most expensive of all gems (with the one exception - very rare colored diamonds, such as red). It is safe to say that, outside of museums, most people never see either large or fine rubies. Most of the material sold today is commercial quality, usually small and heavily included. Ruby its name from the Latin word "ruber" or "rubeus" translated as "red".


The formula for Ruby is a Variety of Corundum, Al2O3, Corundum-Aluminum Oxide. Ruby is the red variety of corundum, the second hardest natural mineral known to mankind. The non-red variety of corundum is Sapphire. Sapphires are well known among the general public as being blue, but can be nearly any color. The red color in ruby is caused by trace amounts of the element chromium. The best shade of red for ruby is often given the name "pigeon blood red", but ruby can be any shade of red up to almost pink. Oriented rutile crystal inclusions cause a six-rayed-star light effect (called asterism) to form the popular Star Ruby. Legends, Myths and Healing Properties:

RubyRubies have a famous place in science - the first lasers were made from artificial ruby crystals. They still are used for this purpose although other materials offer improved efficiency. According to legend, Ruby is said to accord wearers wisdom, happiness and health, and to bring particularly good luck to gamblers and lovers.

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All rights are reserved by original sources.
Smithsonian Institute 1998-2005 Bernardine Fine Art Jewelry. 1999-2004 Jewelry Central, JC Store.
2004 Amethyst Galleries, Inc. 1995-2005 Loretta Elaine's Gems for Friends.