December Birthstones December 11, 2017 – Posted in: Jewelry Blog

Those born in December are lucky enough to claim three birthstones, zircon, turquoise and tanzanite. All three December birthstones feature substantially different looks and qualities, from the vibrant blues of turquoise and tanzanite to zircon’s wide range of hues.

Zircon is the oldest of the three stones, dating back over 4.4 billion years. Following behind is Turquoise, which dates back as far as 3000 BCE. The youngest is Tanzanite, which wasn’t found until 1967. Recently, some people have started to add Blue Topaz to the list of December Birthstones.

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What are the Birthstones for December?

December Birthstones Tanzanite Turquoise Zircon

Birthstones have long been a staple gift and accessory associated with each month of the year. Their existence dates back to Earth’s early years. Meanwhile, the concept of birthstones traces back as early as biblical times. Some say their origins lie within the Bible, which details the special garments made for Aharon, the High Priest of the Jews. His breastplate contained 12 gemstones, one for each tribe of Israel.

Throughout the years, cultures have disagreed over the months that each birthstone corresponds to. This is why you will find that they have changed over time. Now, most will agree to the birthstone calendar used today. December is one of the most famous months when it comes to birthstones. It may be because a lot of shopping occurs during December or it might be because of the fascinating stones that showcase that month.

These are the Birthstones for the month of December:

  1. Zircon
  2. Turquoise
  3. Tanzanite
  4. Blue Topaz (although it is heavily disputed)
Blue Topaz Gold Ring
Blue Topaz is also the birthstone of December. Click here to learn more about this ring.

1. December Birthstone: Zircon

Zircon Stone Round Cut

History of Zircon

Unbelievably, zircon is the oldest known material on Earth. (Even older than the moon!) The oldest fragment of zircon, found in Australia, formed at a very early stage of our planet. Zircon is also found in Burma, Brazil, Cambodia, Korea, Madagascar, Mozambique, Nigeria, Sri Lanka, Tanzania, Thailand, and Vietnam.

Zircon was only selected as a December birthstone in 1952 by the Jewelry Industry Council of America. Until then, turquoise and lapis lazuli was the designated December birthstones. Zircon is also the 4th wedding anniversary stone.

Myths about Zircon

The folklore surrounding the oldest of the December birthstones developed in the middle ages when the gem began appearing in various religious writings. The stone was believed to protect its owner from harm, death, and poison.

The gem is also thought to spiritually ground those in need, and physically treat low self-confidence and poor balance.

Where Does Zircon Come From?

December Birthstone in Box

Not to be confused with cubic zirconia, the diamond simulant, zircon forms naturally. Because our planet is very geologically active, its crust is constantly being recycled. This makes uncovering how zircon is formed fairly difficult since there is no longer any physical record of that time.

After studying other planets such as the moon, Mars, and Mercury, as well as conducting numerous “what if” studies, most scientists will agree that zircon is formed as a result of tectonic plates colliding. In addition, Earth’s atmosphere was harsh in the early years, contributing to the formation of zircon.

Different Colors of Zircon

Zircon comes in many colors, which vary based on the conditions during formation. In its purest form zircon will appear colorless. Blue is by far the most popular color of zircon, especially as a December birthstone. This makes Cambodia and Burma major contributors to the gem’s trade.

The zircon that occurs in these parts of the world is naturally red or brown in color. After heat treatment, they turn a vibrant blue. Other colors may also be heat treated for color improvement, however red and brown turn the blue that we know today as December’s birthstone.

Physical Properties of Zircon

Another interesting thing about zircon is that its physical properties have a much wider range than most other gemstones. For example, specimens of zircon may range anywhere from 6.5 to 7.5 on the Mohs Hardness Scale. This means the stone is about as durable as steel, but may still be damaged by other materials that rate higher on the scale, such as diamonds.

As far as appearance is concerned, zircon has a high refractive index, dispersion rating, and strong pleochroism. This means the stone reflects light well, exhibits fire and brilliance similar to a fine diamond, and is known to change colors at different angles of viewing. For these reasons, the stone is fairly valuable compared to other fine gems.

Zircon In Jewelry

Zircon Birthstone in Ring

Stone Cut of Zircon

Because zircon may appear different colors at different angles, the stones must be cut with great care. Colorless zircon is often brilliant-cut, while colored zircon is often emerald step cut. Round zircon stones are usually given a zircon cut, which is a standard round brilliant cut with an extra row of facets at the edges. The most common shapes of zircon include oval, round, pear, emerald, and trillion.

Clarity & Color of Zircon

Zircon is generally both transparent and translucent. It has a brilliant, vitreous sheen when polished.

Some zircon may contain radioactive elements, thorium, and uranium, which cause the crystal structure to break down over time. These stones will be near-amorphous and appear low luster and low green in color.

These rare forms of zircon are not dangerous and are highly regarded amongst jewelers and collectors. Zircon stones with cat’s eye chatoyancy are also a rarity. This December birthstone’s different colors are caused by impurities in the stone.

Carat Size of Zircon

The size and weight of colored stones are often unrelated. For that reason, colored gemstones should be purchased based on size, not carat weight.

Picking the Right Zircon For You

Zircon has a good hardness but is often too brittle for open settings. It is recommended that the stone is worn in protective settings or only as occasion jewelry. Because the gem is very dense, it is usually small in most jewelry. Large stones will be heavy and should be worn on sturdy brooches or thick chains.

Most often, blue zircon is worn in earrings and rings as December birthstone jewelry. Colorless zircon is often worn on bridal jewelry as a high-quality diamond substitute. Luckily, zircon comes in many colors and is therefore extremely versatile in style.

Caring for and Cleaning Zircon

Zircon is fairly easy to care for. The stone is durable but can still be damaged. It should be stored away from your other jewelry and removed when cleaning, gardening, or completing any other hazardous tasks. Zircon is also sensitive to ultraviolet and sunlight. It should not be worn outside for long periods of time.

To clean the stone, gently soak in warm water and wash with mild soap. Pat to dry. Follow up by cleaning the metal it is set in accordingly. Although you might only wear your zircon jewelry in December, you should clean your fine birthstone jewelry frequently as recommended by your jeweler.

2. December Birthstone: Turquoise

Antique Persian Turquoise Brooch

History of Turquoise

Turquoise is the second oldest December birthstone and the 11th wedding anniversary stone. Despite dating back to 3000 BCE, the stone is actually one of the first gems to ever be discovered. Turquoise was considered a holy stone by ancient cultures and often adorned royal figures and leaders. Most notably, King Tut’s burial mask was jeweled in turquoise.

Turquoise did not become one of December’s birthstones until 1912 when the American National Association of Jewelers replaced bloodstone and ruby with turquoise and lapis lazuli.

Myths About Turquoise

Sterle Turquoise Brooch
A rare Sterle’ Sterle Turquoise Brooch, adorned with gold and diamonds

In most cultures, turquoise was believed to hold protective powers. The stone was often placed on weapons, crowns, jewelry, and buildings. In Native American culture, it was also carved into shapes, which were used as family heirlooms and in rituals.

In addition to protection, the stone was also said to cultivate happiness, health, and harmony. For that reason, turquoise was often gifted to those getting married or celebrating a birthday. The gem was considered anti-inflammatory and detoxifying. Turquoise was used to fight viral infections and ward off depression and anxiety in ancient cultures.

Where Does Turquoise Come From?

The name turquoise is fairly new. It is a French word meaning “stone from Turkey” that was created in the thirteenth century. The gem was brought over from Turkey to Western Europe during that time.

This December birthstone is most commonly mined in the Southwest United States. These turquoise mines were opened by the Anasazi in 1000 AD. Other common areas of occurrence include Mexico, Iran, Serabit el-Khadim in the Sinai Peninsula, Egypt, and Israel.

Turquoise forms when water containing copper and aluminum seeps through rocks. The gem forms in veins inside the rock. Eventually, if enough veins form in one rock at once, they become a clump of turquoise.

The popular December birthstone is then polished or sliced. Naturally, turquoise appears waxy and porous. In order to enhance its appearance and increase stability, the stone may be treated with plastic lubricants and dyes.

Physical Properties of Turquoise

Bulgari Turquoise Ring

Turquoise containing high levels of copper appear bluer. Stones with high iron levels appear greener. Less common is turquoise that contains high levels of zinc. In these cases, the gem will appear more yellow.

This gemstone is most often identified by the thin, intricate veins called matrix that run through it. Turquoise matrix are small remnants of the rock it formed within. Some jewelers and collectors consider these veins what make the stone so unique and valuable, while others consider them blemishes that decrease the stone’s value.

Turquoise is on the low end of the Mohs Hardness Scale, scoring a 5-6 on average. Some variations of the gem can score as low as a 3. This means that the stone is easily scratched or broken.

Turquoise In Jewelry

Onyx and Turquiose Necklace

Turquoise is one of the only gemstones not judged by the 4 C’s. This is because the physical properties of the stone vary so greatly. Instead, the categories color, matrix, hardness, and size determine the value of turquoise. This December birthstone is considered most valuable when it is bright robin’s egg blue. Other color variations such as green and yellow lower the value of the stone.

Turquoise matrix is considered valuable in some places, and not in others. Generally, in America, matrix tends to lower the value of the stone. Although, traditional Native American jewelry celebrates the natural veins and webs that appear in the gem.

Depending on the conditions during formation, turquoise may be anywhere from fragile to durable. Turquoise with a high Mohs Scale rating and solid durability is considered the most valuable. The higher the rating, the more long-lasting the stone will be.

How to Shop for Turquoise?

Holding an Vintage Bulgari VCA Cocktail Ring
Rare Bulgari Turquoise Cocktail Ring. Click here to view more.

Just like its sister December birthstone, turquoise is also priced by size not carat weight. Additionally, color plays a major role in pricing this gemstone. You should always look into the different variants of turquoise to determine which one you like best.

The Turquoise Quality Index is used by many to determine the stone’s quality. This is a scale between 8 and 100 that considers eight factors within two categories. Each factor is weighted according to importance. The higher the total score, the more valuable the stone.

Category one, structure, is composed of hardness, enhancement, composition, and cut. Together, this category is worth up to 55 points. The second category, rarity, rates a stone’s availability, color, matrix, and contiguous size. This category is worth up to 45 points.

Caring for and cleaning Turquoise

Although turquoise is more delicate than other gemstones, it is cleaned similarly to most jewels. This December birthstone is quickly cleaned by soaking in warm water and gently washing with mild soap.

Use caution when washing and wearing, as many turquoise stones are treated with dyes and plastics, which will deteriorate if exposed to steam, heat, or other chemical solvents. You should never clean turquoise with an ultrasonic cleaner.

When wearing your new December birthstone, keep in mind that it is fragile. You should avoid exposing turquoise to chemicals, cosmetics, heat and even natural skin oils. These will likely change the color of the stone.

3. December Birthstone: Tanzanite

Tanzanite Ring

History of Tanzanite

Tanzanite is not only December’s newest birthstone but was also only recently discovered. The stone is said to have formed with the first eruption of Mount Kilimanjaro. More than 500 million years later, the first sample of tanzanite was found.

Despite being found in the late 1960’s, tanzanite did not become one of December’s birthstones until 2002. The American Gem Trade Association named it the third birthstone alongside zircon and turquoise. It is also the 24th wedding anniversary stone.

Myths about Tanzanite

Tanzanite can only be found in Tanzania. Because we have only known of the stone’s existence for about 50 years, folklore and legends have not developed. Healers believe the stone carries both physical and mental soothing and calming properties. It is used to resolve issues of communication and interpersonal qualities.

Where Does Tanzanite Come From?

This December birthstone is particularly unique in that it only forms in Tanzania. In 1967, a giant fire scorched most of the grass and earth surrounding Mount Kilimanjaro, revealing the rare stones. They had turned a bright blue-violet after being subjected to heat, making them easy to spot.

Maasai herders who were tending to their livestock first found the stones. After notifying prospector Manuel d’Souza, the government quickly approved permits to begin mining. They initially thought they were mining sapphire but soon realized it was a never-before-seen variation of zoisite.

More than 2 million carats of tanzanite was mined before the local government began regulation. In a 2012 independent study, it was found that just one of the four tanzanite mining blocks will deplete in about 30 years at current production rates.

Colors of Tanzanite

Tanzanite Ring with Halo of Diamonds

Tanzanite generally appears violet-blue in color, but will occasionally feature natural burgundy or brown hues. Some tanzanite is heat-treated within the earth and does not need further treatment. Others need to be heat-treated to bring out the blues that make them so valuable.

December’s youngest birthstone does not follow the same process as other heat-treated gems. While others are treated at over 1,000 degrees Fahrenheit for several days, tanzanite is treated around 600 degrees for less than one hour. Only very rarely is tanzanite not heat treated.

Physical Properties of Tanzanite

Tanzanite lands at about 6.5 on the Mohs Hardness Scale. It is fairly durable but is still susceptible to surface damage if dropped or scratched.

The stone naturally ranges from blues to violets. This makes them great alternatives to sapphires, aquamarines, and blue topaz. Tanzanite has strong pleochroism, meaning it reflects different colors at different angles. It is also dichromatic, meaning it absorbs rays of light in different amounts.

Tanzanite In Jewelry

Tiffany & Co. Introduced the World to Tanzanite.

In 1968, just one year after the first tanzanite gemstones were found, Tiffany & Co. made a deal to become the stone’s international distributor. Soon after, the company began releasing exclusive pieces of fine tanzanite jewelry. In their widespread publicity campaign, they frequently used the phrase “Tanzanite can only be found in two places, Tanzania and Tiffany’s.”

The Four C’s

Tanzanite and Diamond Ring

Tanzanite is most valuable when it appears a deeply saturated blue-violet. Paler variations are more inexpensive. Due to the stone’s ability to reflect different colors at different angles, the way it is cut is of utmost importance. Bluer stones are more valuable, so lapidaries will often make precise cuts that reflect this color more.

Tanzanite rarely has visible inclusions, so when they do occur it lowers the value significantly. The bluest stones are normally over 5 carats. Smaller stones are often less vibrant in color.

Picking the Right Tanzanite For You

The newest December birthstone is available in such limited quantities and is growing in popularity. For these reasons, it is considered a very rare jewel. Because it only forms on a small stretch of land in Tanzania, the stone’s price and availability are entirely dependent on what happens there.

It is important to know how to safely set tanzanite. It is recommended that you wear the stone in necklaces or earrings as opposed to rings, for less exposure to wear and tear. However, if you choose to purchase a ring, simply ensure that your stone is in a protective setting.

Smaller stones are usually bluer and therefore more valuable. Keep this in mind as you select your gem.

Caring for and cleaning Tanzanite

This December birthstone is generally safe for everyday wear but should be removed for strenuous activity or when you are using chemicals of any kind. Tanzanite has good color stability and will not change under normal light exposure or in normal temperatures.

Like with most stones, regularly cleaning is necessary to keeping your tanzanite looking its best. Gently wash with warm water and mild soap.

Final Thoughts on December Birthstones

Whether you’re gifting a stunning December birthstone to your favorite birthday girl, congratulating a couple on a special wedding anniversary or simply investing in some December jewelry for yourself, you should always feel confident when purchasing. We hope this guide helps you better understand the three beautiful December birthstones.

Gift a December birthstone this winter!