The word “zircon” most likely comes from the Persian word zargun meaning “golden colored.” Zircon colors can be: blue, red, orange, yellow, brown, and green. Colorless zircon is known for its brilliance and flashes of multicolored light, called fire. Zircon comes from Sri Lanka and Australia (known for producing zircon birthstones in yellow-brown, orange brown, pink, and purple). This December birthstone is often located near sapphire sources. Countries where the two gems overlap include Myanmar, Vietnam and Cambodia. Zircon ranges from 6 to 7.5 on the Mohs scale of hardness. It is commonly heat treated to produce blue, colorless, orange, yellow and red stones. Some heat-treated stones may revert to their original colors (usually light brown) after prolonged exposure to bright light. Exposure to heat can alter the color of some zircon. Because zircon tends to be sensitive to impacts, avoid wearing it in rough conditions.

Tanzanite was one of the gem discoveries of the 20th century. Blue stones emerging from Tanzania were identified as the mineral zoisite in 1962. Not until 1967, did people locate the primary source of the Merelani Hills and it is the only place on earth where tanzanite is mined comercially. It was named tanzanite in honor of its country of origin. The color ranges from blue to violet, with the blue considered the most valuable. It ranges from 6 to 7 on the Mohs scale of harness and is resistant to the effects of normal heat, light and common chemicals. It may crack if exposed to very high temperatures or sudden temperature changes, and it abrades easily. Most tanzanite begins as brownish zoisite that is heat treated to produce the blue to violet hues that characterize this December birthstones and the resulting color is permanent. It is also the gem for the 24th wedding anniversary.

Turquoise is a semi-translucent to opaque gem that ranges from blue to green. It often has veins of other minerals or from the rock in which it is formed. The name means “Turkish stone” because the trade route came to Europe through Turkey. New Mexico was the largest producer of turquoise in the U.S. until the 1920s, but today most of it comes from Arizona and Nevada. It has a Mohs hardness range of 5 to 6 and is porous. Some turquoise is treated to improve its durability and appearance. Turquoise can be dyed or chemically enhanced by adding an epoxy or acrylic resin for greater hardness or better color. Turquoise is generally stable to light, but high heat can cause discoloration and breakage. Turquoise can be damaged by acids and it can be discolored by certain chemicals, cosmetics and even skin oils or perspiration. Turquoise is also the gem of the 11th wedding anniversary.

Clean any of the three December birthstones using a soft brush and mild soap in warm water.