Rubies are used in jewelry.
Ruby is the birthstone for July and for the Cancer horoscope sign. It is red corundum or crystalline aluminum oxide, a naturally-occurring mineral in some areas of the world. Rubies occur naturally in shades from pink to purple. The most desirable color is a deep blood red with a bluish hue, often called a Burmese ruby, according to Minerals.net website.Scholars believe the tradition of birthstones comes from the Bible and the Breastplate of Aaron, according to the University of Texas Department of Geological Sciences. The Breastplate of Aaron had 12 gemstones, representing the 12 tribes of Israel, reported in Exodus 28: 15 to 30. Does this Spark an idea?
Physical Properties
Rubies are a nine on the Moh's hardness scale, one of the hardest stones available. The specific gravity or density ratio compared to water is from 3.9 to 4.2, often seen as 4.0, as this is an easy average to remember. The composition is Al2O3 or aluminum oxide. The refractive index is 1.76 or 1.77, and this is the ratio of the velocity of light in the air in relation to the velocity of light in the ruby. A refractometer looks much like a microscope, but reads the refractive index.
Folklore
In addition to the July birthstone, ruby also is the gift of choice for wedding anniversaries, both the 15th and the 40th. The red is symbolic of the eternal flame. Protection from danger for the owner, harmonious living with his fellowman and financial security are qualities bestowed by the ruby in folklore, according to the Atkins Jewelry website.
Mining
Rubies are gem corundum mined from gem gravel deposits. Burma, now Myanmar, was for years the most prolific source for quality rubies, with Thailand, Sri Lanka and India with some production. The University of Texas Department of Geological Sciences reports that synthetic corundum diminished Myanmar production and it never regained the prominence the country held at the beginning of the 20th century. Recent mines are in Australia, Kenya and Tanzania, according to the University of Texas Department of Geological Sciences.
Synthetic Rubies
Flame fusion and flux growth laboratory-synthesizing processes make rubies for jewelry and industry. Industrial uses for synthetic rubies include jewel bearings in watches and instruments and windows in optical scanning devices.
Color
Rubies are shades of pink and red, and are distinguishable from other red stones such as spinel, garnet, tourmaline or glass by the hardness and the refractive index. For example, garnet is 7.5 on the Moh's scale and ruby is 9.0. Heat treatment and irradiation techniques may alter real rubies to create more intense color. Treated rubies and synthetics are detectable with a microscope and a trained eye, based on inclusions and crystal growth patterns.
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