Article
Article
Ruby
Article By:
Liddicoat, Richard T., Jr. Gemological Institute of America, Los Angeles, California.
Last reviewed:January 2020
DOI:https://doi.org/10.1036/1097-8542.595500
The red variety of the mineral corundum, in its finest quality the most valuable of gemstones. Only medium to dark tones of red to slightly violet-red or very slightly orange-red are called ruby (see illustration); light reds, purples, and other colors are properly called sapphires. In its pure form the mineral corundum, with composition Al2O3, is colorless. The rich red of fine-quality ruby is the result of the presence of a minute amount of chromic oxide, usually well under 1%. The chromium presence permits rubies to be used for lasers producing red light. See also: Laser; Sapphire
The content above is only an excerpt.
About AccessScience
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information
