Birthstone Spotlight: December Tanzanite, Zircon, or Turquoise

tanzanite blue zircon turquoise december birthstone

Having a December birthdate I’ve always been interested in the birthstone for my month. My first experience with a birthstone came from my dad’s trip to Texas back in the way back day. He stopped in Arizona along the way and bought me a turquoise ring. Wow! That was cool. I don’t remember the year but it was a number of decades ago. I am guessing I was all of 6 years old or so. It was a cool ring in the Southwest Native American style. I began to learn about birthstones.

The tradition I was taught as a young person was that December had two birthstones: zircon and turquoise. Well that tradition has had some issues.

Blue zircon has been very difficult to find and so has not been readily available for December babies. Turquoise being an opaque gem has had its detractors. While I think this is an unfair assessment of turquoise it is true that most months have crystalline transparent (read: more expensive) gems as their birthstone.

In that vein turquoise which is both opaque and affordable has seemed not quite on a par with those months which have diamond, ruby, emerald or sapphire as the birthstone—can you imagine having one of those “big-four” as your birthstone?

The answer to this issue has been the addition on some birthstone lists of Tanzanite as an alternative birthstone for December. So, now those of us born in December have three wonderful gems from which to choose—and they are all three wonderful. This blog post will give you a little bit of education about all three.

Tanzanite as the December Birthstone

Tanzanite roundTanzanite is not only a newcomer to birthstone lists but a newcomer to the gem world as well. Tanzanite was discovered in 1967 in Tanzania, East Africa. Tanzanite is considered to be a one-location gem. That means that from a commercial perspective there is only one source of tanzanite in the world.

I couch that in qualified terms since many minerals may exist in small quantities or ultra small crystals in locations other than those locations which produce gems which reach the world marketplace. In all practicality tanzanite has only come from one source and that makes the gem very interesting from a collector’s standpoint.

In addition to its unique source, tanzanite is blessed with a color that virtually everybody likes. The universal attraction to tanzanite’s color has made this gem instantly popular throughout the world. In the gem world it was thought that tanzanite would be an affordable alternative to sapphire. Back in the late 60’s and early 70’s sapphire was very hard to find and a good naturally mined gem alternative was viewed in a positive light. However, it seems now that tanzanite stands on its own with its own reputation.

Zircon as the December Birthstone

Blue ZirconWhile zircon comes in a number of colors it is the blue color in zircon that is the originally intended birthstone. As we can see by the color palette of December alternatives we are in the part of the palette called cool colors. No doubt that has to do with the cooler temperatures associated with December in the Northern Hemisphere.

While zircon has been mined in different localities of the world it is the production from Cambodia that has traditionally furnished us with the blue gems we have known as the true December zircon. As we have discussed through the years there are many processes known as treatments which can affect the color of gems somewhere between the mine and the marketplace.

Blue zircon from Cambodia comes out of the ground a brown color. Usually while still in the rough the stones are heated. A certain percentage will generally turn blue. Gems resistant to the treatment will be heated again and perhaps again with the resulting gems turning yellow or white. Colorless zircons have been used for centuries as a diamond substitute. Zircon has the highest refractive index amongst well known gems giving it a look that can pass for diamond at a quick glance. Zircon also is highly dispersive which is to say it has a lot of the “fire” associated with diamond. Dispersion is the breaking up of light into the rainbow of colors that is so notable in diamond.

Blue zircon gems are really quite rare in big sizes. We counted ourselves lucky in years that we could have a nice supply of gems over 5 carats. On occasion we’ve been able to get intense pure blue gems over 20 carats and knew we had a real collector item in hand.

Zircon is a silicate mineral as are so many gemstones such as: the quartz gems, garnet, topaz, tourmaline and so forth. Silicate minerals all have silicon and oxygen atoms as part of their composition. What is seemingly odd is that zircon is found all over the earth as part of granite and in sedimentary formations as well. Generally though these are micro-crystals and not of much use in jewelry. It is usually in pegmatitic formations that the larger crystals can be found. This seems logical when you take into account that pegamtites are the nurseries for tourmaline, aquamarine, and topaz crystals as well.

Turquoise as the December Birthstone

Blue turquoiseAs a gem, turquoise has to be one of the oldest in use as jewelry. Archeology has brought us evidence of turquoise being used for jewelry as long as 5,000 years ago. Turquoise comes out of the ground in its beautiful blue color that is slightly touched by green. Also, turquoise is relatively easy to work with being between 5 and 6 in hardness.

While turquoise can come in gems that are predominantly green, the birthstone color is generally thought of as the more predominantly blue color. This goes along with the use of the cool color palette for December birthstones. Being an opaque gem turquoise is generally cut en-cabochon with a domed top sloping down and slightly out. However turquoise is popular in inlay jewelry as well in which case the gems are cut with a flat top so they will fit into the spaces of gold or silver from which the jewelry is made.

A short list of places where turquoise mines have been worked includes Africa, Asia, Australia and North America. Since turquoise comes out of the ground with an attractive color and is easily worked it is no wonder that it was popular beginning in ancient times. In mineralogical terms turquoise is a hydrous phosphate of copper and aluminum. Since these components are relatively available in the earth’s crust it is perhaps no wonder that turquoise comes from many different sources. This is in contrast to other gems which are comprised of components less frequently encountered.

For students of gems Persia is the ancient source of the best turquoise. Since Persia is currently known as Iran we can all understand why there might be issues of getting this particular gem to market around the world. What a shame since that material is truly amongst the best. But then, politics has spoiled more important things from time to time.

Currently the most important source of turquoise is the southwest United States. Arizona is the best known current USA producer but mines in Colorado, California, New Mexico have also played an important part in supplying turquoise from time to time.


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© Ramseygems.com, Inc., 2013. Unauthorized use and/or duplication of this material without express and written permission from John and Laura Ramsey is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to johnandlauraramsey.com with appropriate and specific links back to this original content.

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