Blue zircon and blue topaz make popular jewelry items.
Blue zircon and blue topaz are gemstones that have become increasingly popular in jewelry in recent years. They are used to make cufflinks, bracelets, rings, earrings and pendants. Both blue zircon and blue topaz appear similar but have distinct physical and chemical properties.
Physical Properties
Blue zircon measures 6.5 to 7 on the Mohs hardness scale (which lists minerals on the basis of their scratch resistance), has a specific gravity of approximately 4.15 and a refractive index that ranges from 1.77 to 1.98. Blue zircon reacts poorly to heat and may lighten in color upon prolonged exposure to excessive heat.
Blue topaz measures 8 on the Mohs hardness scale, has a specific gravity, or density, that ranges from 3.56 to 3.57 and a refractive index between 1.61 and 1.62.
Formation
Zircon is a naturally occurring gemstone known for its diversity of color. Red, brown and gray brown zircons are the most commonly occurring natural varieties of the stone. Blue zircon, also called starlite, is produced when brown, red, reddish brown or partially transparent zircons are heated (at temperatures ranging from 1,472 degrees Fahrenheit and 1,832 degrees Fahrenheit) in the absence of oxygen.
Topaz is a naturally occurring birthstone that exists in a variety of colors--including orange, red, violet, brown, pink, green and yellow. Naturally found blue topaz is extremely rare and most commercially available varieties are produced when colorless or white topaz is irradiated with gamma rays.
Birthstone
Blue zircon is the birthstone for December, while blue topaz is a November birthstone.
Occurrence
Zircon is mined primarily from Burma, Cambodia and Africa.
The main sources of blue topaz are Brazil, United States and Burma.
Formula and Chemical Makeup
The chemical formula of blue zircon is ZrSiO4. It is a mixture of silicon dioxide (SiO2) and zirconium oxide (ZrO2).
The chemical formula of blue topaz is Al2(F,OH)2SiO4. It is an aluminum silicate mineral that is made up of 56.5 percent aluminum oxide (Al2O3), 33.3 percent silicon dioxide (SiO2), 10 percent (iron) F and 10 percent hydroxide (OH).
Metaphysical Properties
Blue topaz is associated with heightened humor, calmness, self-expression, communication and understanding.
According to Isabel Bellamy and Donald MacLean in the book "Radiant Healing," blue zircon fosters praying and spirituality.
Hazardous Information
According to Antoinette Matlins and Antonio C. Bonanno in the book "Jewelry & Gems, the Buying Guide," deeper blue topazes that endure extensive heat treatment are found to be radioactive--a fact verified by the Nuclear Regulatory Commission. Blue topaz bought outside the United States must be tested for its level of radioactivity.
Zirconium contains trace amounts of radioactive elements but their values are commonly too low to cause any danger.
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