What are December’s birthstones? | Zircon & Tanzanite

Happy Birthday to our December babies! It may be cold outside, but the birthstones for this month are fiery, brilliant, and beautiful. Zircon and Tanzanite share the honor of representing this month. Learn more about the color, origins, history, and folklore behind the stones in this blog!


Zircon’s natural colors include yellow-golden, red, blue, and green. The colorless version of this stone can be mistaken for a diamond and are sometimes called “Matura diamond.”

Zircon color range

Tanzanite ranges in color from deep ultramarine to light violet-blue, it is also a trichroic gemstone that shows flashes of blue, violet, and red.


Zircon is found in many countries around the world including Australia, Madagascar, Tanzania, Myanmar, China, and Cambodia.

Tanzanite is only found on the African continent in the Merelani Hills (home to Mount Kilimanjaro) in Tanzania. Mount Kilimanjaro is one of three freestanding volcanic peaks that are the result of massive tectonic activity that created one of the most mineral-abundant locations on earth known as the Mozambique Orogenic Belt. With all the folding and faulting that took place millions of years ago, different combinations of minerals were able to form and reform, producing Africa’s rich gemstone deposits.

Tanzanite rings


Zircon has been used in jewelry for many centuries. It was popular in the Victorian Era for its lovely blues. Zircon has double refraction and is known for its multicolored flashes we call fire.

Tanzanite was first discovered in1967 in northern Tanzania by a tailor and part-time gold prospector. Officially called blue zoisite it was popularized as tanzanite by Tiffany & Co. who promoted the rarity of the gem.

Zircon Fun Facts:

Zircon ring
  • The various impurities found in zircon material are what cause its various range of colors.
  • In the Middle Ages, zircons were believed to help induce sleep and promote honor and wisdom in the wearer.
  • Zircon is the oldest mineral on Earth, samples in Australia have been found that are over 4.4 billion years old.
  • Green zircon is rarely seen in the gem trade and highly sought after for it rich, warm green hue and deep color saturation.
  • Blue zircon is often produced by heating the more commonly occurring brown zircon. However, only some of the brown material possesses the necessary chemical structure to produce the sought after teal blue color and typically these deposits are only found in South East Asia. This is why most blue zircons are sourced from Cambodia or Burma (Myanmar).
  • The double refractive property (the way and speed at which it bends light in multiple directions) is responsible for the diamond-like sparkle you see in well-cut zircon.
  • Since zircon is not a very well know gem, it is often unfairly confused with the popular diamond imitator, cubic zirconia (CZ).

Tanzanite Facts:

• The much-prized stones are found only in the foothills of Mount Kilimanjaro.
• Tanzanite is considered a generational heirloom gemstone. Because the gem is found and mined only on a 4 square kilometer plot of land, after 10 to 20 years, there will be none left to be mined

•The largest tanzanite crystal TheMawenzi was found in 2005 and weighed 16,839 carats. The world’s largest faceted tanzanite is 737.81 carats.
• This blue/purple gemstone is said to strengthen the immune system, detoxify the blood and improve vitality. It also believed to aid in overcoming communication difficulties and promotes compassion.
• The Queen of Kilimanjaro is a 242-carat centerpiece set in a tiara accented with 803 brilliant cut tsavorite garnets and 913 brilliant cut diamonds. This piece is in the collection of Michael Scott, the first CEO of Apple Computers.

Zircon Hardness: 6-7.5

Care: Handle with care, can scratch, avoid high heat, and avoid ultrasonic cleaners. Use mild soap and a soft cloth to clean.

Tanzanite Hardness: 6.5

Care: Avoid ultrasonic or steam machines and swift temperature changes. Use any plain soap and water to clean. Be sure to thoroughly rinse and dry all your jewelry after cleansing.

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