Zircon is a famous gem of many colors, known for hundreds of years for its luster and fire. It is often looked upon as a cheap diamond simulant, but is, in fact, a valuable gem. Its color diversity is caused by traces of certain elements, some of which are radioactive. Zircons containing radioactive elements undergo a process called metamiction, in which their inner crystal structure becomes destroyed. These radioactive forms of zircon must be heated to stabilize them for use as gems. In fact, almost all gem forms of zircon (even those that are not radioactive) are heat-treated to enhance their color. Heating semi-transparent, grayish-brown or reddish-brown zircons from most localities in an oxygen-free environment gives them a blue color. If these blue stones are then re-heated in air, their color turns golden-brown. Heat-treatment of certain zircons also produces colorless gems.

Zircon comes closer to resembling diamond than any other natural gem. Its powerful luster and intense fire gives it splendor that no other natural gem but diamond can surpass. However, its popularity is diminished by the fact that it is often perceived as an inexpensive diamond imitation. Colorless zircon is easily distinguished from diamond by its strong double refraction and lower hardness.

The brilliant luster and fire of zircon, combined with its hardness and range of colors makes it a most desirable gem. However, it does have some undesirable traits. An interesting and strange habit exhibited in only few zircons is that their color darkens and their luster dulls upon prolonged exposure to sunlight. This effect can be reversed by giving the stones a second heat-treatment. It is also prone to cracking and chipping if banged too hard. For this reason, care must be taken when cutting zircon. Zircon must also be cut in a manner in which its strong double refraction is least noticeable, to prevent it from appearing blurry.

USES
Zircons of all colors are used as gems, but the colorless, golden-brown, and blue gems are the most popular. Colorless zircon is usually cut with the brilliant cut. This brings out its fire to its fullest capability. It is often used as a cheaper, yet natural alternative to diamond. Golden-brown zircon is very popular in the jewelry market, and blue zircon is also a favorite. The other color forms (yellow, green, pink, and purple) are occasionally seen in jewelry.

VARIETIES
Hyacinth or Jacinth - yellow, orange, brown, or reddish-brown variety of zircon. Most often refers to the golden-brown form. Occasionally also refers to topaz with a yellow to reddish-brown color
Jargon or Jargoon - colorless to pale gray or pale yellow variety of zircon
Starlite - blue variety of zircon
Matarua, Matara, or Matara Diamond - colorless zircon used to resemble diamond

SIMILAR GEMSTONES
Because zircon occurs in so many colors, there are many gemstones that resemble it. First and foremost, colorless zircon resembles diamond. It also resembles synthetic diamond simulants such as cubic zirconia and strontium titanate. It is distinguished from colorless gem forms of other popular gems (such as sapphire, beryl, topaz, and quartz) by its greater luster.
Golden-brown zircon is similar to topaz, citrine, and sapphire.
Blue zircon is similar to aquamarine, topaz, indicolite tourmaline, and blue spinel
Yellow zircon is similar to yellow diamond, yellow sapphire, heliodor, chrysoberyl, and topaz
Green zircon is similar to demantoid garnet, peridot, and tourmaline
Pink zircon is similar to rose quartz, morganite, kunzite, spinel, and topaz

ALSO SEE

• The mineral Zircon
• Diamond

PICTURES

Special thanks to Gem Hut for most of our gem images. The gems displayed or others like them can be purchased through Gem Hut by clicking the link below each picture.

Picture: Light blue Zircon
Size: 1.72 ct. (both gems)
Cut: Brilliant
Gem: Gem Hut

Picture: Blue Zircon
Size: 8.73 ct. (both gems)
Cut: Oval
Gem: Gem Hut

Picture: Reddish-brown Zircon
Size: 8.82 ct.
Cut: Fancy (checkerboard)
Gem: Gem Hut

Picture: Greenish Zircon
Size: 1.27 ct.
Cut: Oval
Gem: Gem Hut