December is a unique month in the world of birthstones, possessing not one, but three recognized gems: turquoise, tanzanite, and zircon, with blue zircon being particularly prominent. This selection reflects a fascinating evolution in birthstone traditions, moving from earlier associations with ruby to the modern inclusion of these vibrant and historically significant stones. The month, derived from the Latin decem meaning “ten,” is a time of year symbolizing change, camaraderie, and festive gatherings, qualities mirrored in the diverse characteristics of its birthstones. This article will explore the history, geological origins, gemological properties, and cultural significance of these three December birthstones.
History and Lore
The designation of birthstones has a long and evolving history. Early birthstone lists, inspired by Biblical texts, initially assigned ruby as the stone for December. However, over time, these associations shifted. By 1870, turquoise had emerged as a primary December birthstone, as documented in Tiffany & Co.’s “Gregorian Birthstone Poems.” The National Association of Jewellers (now Jewellers of America) further solidified turquoise’s position in 1912, listing it as the primary stone with lapis lazuli as an alternative. Zircon was added to the list in 1952 by the Jewelry Industry Council of America, and most recently, in 2002, tanzanite joined the ranks of December birthstones.
Turquoise boasts an exceptionally long history of human appreciation, dating back millennia. Ancient Egyptians, pharaohs and rulers alike, adorned themselves with this captivating gem. Chinese artisans were carving turquoise more than 3,000 years ago. Throughout history, turquoise was believed to possess protective qualities, safeguarding wearers from harm – even preventing falls from horses and warning of impending disaster. Hindu traditions associated turquoise with wealth and good fortune when viewed after a new moon.
Tanzanite, in contrast, is a relatively recent discovery. It was first identified in Tanzania in 1962, with the primary source located in the Merelani Hills in 1967. Despite its more recent introduction, tanzanite quickly gained popularity, largely due to the marketing efforts of Tiffany & Co., who recognized its international appeal and launched a major advertising campaign in 1968.
Zircon, while less prominently featured in historical lore compared to turquoise, has a long history of use in jewelry. Its name is believed to be derived from the Persian word zargun, meaning “gold-colored,” referencing one of its common hues.
Geological Formation and Sources
The origins of these three birthstones are geographically distinct, reflecting their unique geological formation processes.
Turquoise forms in relatively dry, arid regions, typically in the vicinity of copper deposits. It is a secondary mineral, meaning it forms from the alteration of other minerals. The presence of copper, aluminum, and phosphate, along with water, are essential for its creation. Turquoise is often found with other secondary minerals like limonite and azurite.
Tanzanite is exclusively found in the Merelani Hills of northern Tanzania. This limited geographical source contributes to its rarity and value. The gem forms within metamorphic rocks, created by intense heat and pressure. The mines are located at the base of the snow-covered slopes of Mount Kilimanjaro, and extraction occurs at depths exceeding 100 meters.
Zircon, unlike turquoise and tanzanite, is found in a wider range of geological settings. It forms in igneous rocks, metamorphic rocks, and even sedimentary deposits. Zircon is a very durable mineral, capable of surviving the erosional processes that destroy many other gems, which is why it is often found as a detrital mineral in alluvial deposits. While blue zircon is a popular variety for December birthstones, zircon naturally occurs in a variety of colors, including golden, red, and clear.
Gemological Properties
Each of these December birthstones possesses distinct gemological properties that contribute to its unique appeal.
Turquoise: Turquoise is a semi-translucent to opaque gem, ranging in color from blue to green. Its color is influenced by the presence of copper and iron. A defining characteristic of turquoise is the presence of matrix, which are veins of the host rock that remain within the gem, adding to its unique character.
Tanzanite: Tanzanite is known for its “velvety” appearance, resulting from its deep and saturated color. It typically exhibits a range of blue and violet hues, with the purest blue shades being the most valuable. Tanzanite is pleochroic, meaning it displays different colors when viewed from different angles.
Zircon: Zircon exhibits a high degree of brilliance and fire, often resembling a diamond. It occurs in a wide spectrum of colors, but blue zircon is particularly favored as a December birthstone. Zircon also displays strong double refraction, meaning light splits into two rays as it passes through the gem, creating a slightly blurred appearance when viewed through the pavilion.
The following table summarizes key gemological properties:
| Property | Turquoise | Tanzanite | Zircon |
|---|---|---|---|
| Chemical Formula | CuAl6(PO4)4(OH)8·4H2O | Ca2Al3(SiO4)3(OH) | ZrSiO4 |
| Color | Blue to Green | Blue to Violet | Various (Blue favored) |
| Transparency | Opaque to Translucent | Transparent | Transparent |
| Hardness (Mohs) | 5-6 | 6-7 | 6.5-7.5 |
Symbolism and Metaphysical Beliefs
Throughout history, these gemstones have been imbued with symbolic meanings and metaphysical properties.
Turquoise has long been associated with protection, health, and good fortune. Ancient cultures believed it could ward off evil and safeguard travelers. It is often linked to communication, creativity, and emotional balance.
Tanzanite is believed to promote self-transformation, healing, and psychic abilities. Some practitioners associate it with activating the throat, third-eye, and crown chakras, facilitating communication with higher realms.
Zircon is often associated with prosperity, wisdom, and honor. Blue zircon, in particular, is believed to promote calmness, clarity, and emotional stability.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of these December birthstones.
Turquoise is relatively soft and porous, making it susceptible to scratches and damage from harsh chemicals. It should be cleaned with a soft cloth and mild soapy water. Avoid ultrasonic cleaners and harsh cleaning agents.
Tanzanite is more durable than turquoise but still requires careful handling. It can be cleaned with warm soapy water and a soft brush. Avoid sudden temperature changes and ultrasonic cleaners.
Zircon is relatively hard and durable, but it can be brittle and susceptible to chipping. It can be cleaned with warm soapy water and a soft brush. Avoid harsh chemicals and ultrasonic cleaners.
Conclusion
The December birthstones – turquoise, tanzanite, and zircon – represent a captivating blend of history, geological wonder, and symbolic meaning. From the ancient protective powers attributed to turquoise to the recent discovery and vibrant hues of tanzanite, and the brilliance of zircon, these gems offer a diverse range of options for those born in the final month of the year. Their unique properties and captivating beauty continue to make them cherished symbols of December’s festive spirit and the promise of new beginnings.