December boasts a unique distinction among the birthstones: it has four officially recognized gemstones – turquoise, tanzanite, blue zircon, and blue topaz – each offering a distinct shade of blue and a rich history. This variety allows individuals born in December to select a stone that resonates with their personal style and preferences. The story of how December acquired this quartet of gems is a fascinating evolution of marketing, geological discovery, and enduring cultural significance.
History and Lore
The longest-standing December birthstone, turquoise, has a history stretching back nearly 6,000 years. Evidence suggests its use as early as 5500 BC, with a bracelet discovered dating back to that period. Ancient Egyptians, calling it mefkat meaning “joy,” mined turquoise in the Sinai desert, crafting it into scarab amulets and associating it with the sky and motherhood goddess Hathor. Persians, referring to it as pērōzah (“victory”), believed it to be a heavenly stone, adorning turbans, weapons, and mosques with it. Ancient Greeks and Romans also valued turquoise, known as callais, creating beads, necklaces, and rings.
Among Aztec civilizations, turquoise held sacred status, believed to be a gift from the deity Quetzalcoatl, and was even buried with rulers. Native American tribes similarly prized turquoise, utilizing it in ceremonial items, talismans, and as a form of currency. The Apache believed attaching turquoise to bows ensured accurate aim.
While turquoise held prominence for centuries, the 20th century saw the addition of other blue gemstones to the December birthstone list. Blue zircon was added in the mid-20th century to cater to those desiring a more sparkling option than the opaque turquoise. The discovery of tanzanite in Tanzania’s Mireland Hills in 1967 prompted jewelers to advocate for its recognition, which was officially granted by the Gemological Institute of America (GIA) in 2002. Finally, blue topaz joined the ranks in 2016, offering an affordable and durable alternative.
The Greek myth of Hyacinth is linked to zircon, symbolizing rebirth. White zircon represents purity, while yellow zircon is known as the “Stone of Prosperity.”
Geological Formation and Sources
The sources for these December birthstones are geographically diverse. Turquoise is found in various locations, notably in the American Southwest, where Navajo silversmiths referred to it as “stone fallen from the sky.” Historically, significant turquoise deposits were mined in Persia and Egypt.
Tanzanite is exclusively sourced from the Mireland Hills of Tanzania, making it a relatively rare gemstone. Blue zircon is found in a variety of locations, though specific mining areas are not detailed in the provided sources. Blue topaz, similarly, has multiple sources, but the provided materials do not specify them.
Gemological Properties
Each of the December birthstones possesses unique gemological properties. Turquoise is graded on color, matrix, and texture, with dense textures exhibiting better polish luster. The most valuable turquoise displays a bright “robin’s egg” or “sky” blue color with even distribution. Green or greenish-blue varieties are more affordable. Medium-dark tones are considered most vibrant.
Tanzanite exhibits a range of purple to blue hues, with vibrant pure blue being the most valuable, followed by bright purplish-blue and violet-blue. The ideal tone for tanzanite is between 75 and 85 percent, and strong pleochroism (color change) enhances its value. Tanzanite typically registers between 6 to 7 on the Mohs scale of hardness. It can be cracked by high temperatures or sudden temperature changes and is susceptible to attack by hydrochloric and hydrofluoric acids. Most tanzanite undergoes heat treatment to enhance its blue to violet hues, a process that results in a permanent color change without affecting durability.
Blue zircon, while available in various colors, is most prized in its blue form. Browns and reddish-browns are common, while vivid greens and reds are more valuable.
The provided sources do not detail the gemological properties of blue topaz.
The following table summarizes the hardness of Tanzanite compared to other common gemstones:
| Gemstone | Mohs Hardness |
|---|---|
| Diamond | 10 |
| Corundum (Ruby/Sapphire) | 9 |
| Topaz | 8 |
| Quartz | 7 |
| Tanzanite | 6-7 |
| Feldspar | 6 |
| Apatite | 5 |
Symbolism and Metaphysical Beliefs
Throughout history, these gemstones have been imbued with symbolic meaning. Turquoise is believed to calm nerves and aid in navigation, making it a talisman for travelers. It is associated with protection, particularly by the Navajo who believed it channeled the protection of thunder gods. Turquoise is also linked to generosity and the pursuit of knowledge, aligning with the zodiac signs of Pisces and Sagittarius.
Zircon, through the Greek myth of Hyacinth, symbolizes rebirth. White zircon represents purity, and yellow zircon is associated with prosperity.
The sources do not detail the specific symbolism or metaphysical beliefs associated with tanzanite or blue topaz.
Care and Cleaning
Proper care is essential to maintain the beauty of these December birthstones. Tanzanite, with a hardness of 6 to 7 on the Mohs scale, requires gentle handling. It is best set in earrings or pendants to minimize wear and tear. Warm, soapy water is the recommended cleaning method; ultrasonic and steam cleaners should be avoided.
Turquoise, with its unique texture, requires careful polishing. The sources do not provide specific cleaning instructions for zircon or blue topaz.
Conclusion
The December birthstones – turquoise, tanzanite, blue zircon, and blue topaz – represent a diverse and captivating palette of blues, each with a unique history, geological origin, and symbolic meaning. From the ancient reverence for turquoise to the modern appeal of tanzanite, these gemstones offer a range of options for those born in the twelfth month of the year. The evolution of December’s birthstone list reflects both changing consumer preferences and the ongoing discovery of beautiful and significant gemstones around the world. Selecting a December birthstone is a personal journey, allowing individuals to connect with a gem that resonates with their individual style and beliefs.