The final month of the year is uniquely associated with a diverse palette of gemstones, all united by the cool, serene hues of blue. While many months are tied to a single gem, December is celebrated for offering a quartet of choices: turquoise, tanzanite, zircon, and blue topaz. This abundance provides a remarkable range of colors, from the soft, earthy tones of turquoise to the vibrant, electric blues of tanzanite and the brilliant sparkle of zircon. Each of these stones carries its own distinct history, geological origin, and set of characteristics, making the selection of a December birthstone a deeply personal decision based on aesthetics, durability, and meaning.
The modern list of birthstones was formalized in the early 20th century, with additions made over time to reflect new discoveries and market trends. In 1912, the National Association of Jewelers established an official list, which was later updated by the Jewelry Industry Council of America in 1952, adding zircon to December’s offerings. The most recent addition was tanzanite in 2002. Blue topaz, while not always listed in the traditional trio, is frequently included in modern compilations, solidifying December’s status as the month with the most birthstone options. This evolution underscores the dynamic nature of birthstone traditions, adapting to incorporate gems that capture the public’s imagination. The following sections explore the history, properties, and significance of each of these captivating blue stones.
Turquoise: The Ancient Sky Stone
Turquoise stands as one of the most ancient and culturally significant gemstones in human history. This semi-translucent to opaque gem, which ranges from sky blue to greenish hues, is often characterized by a matrix of darker veins—the remnants of the host rock in which it formed. Its name is derived from the French pierre turquoise, meaning "Turkish stone," a reference to the trade routes through which the gem was first brought to Europe from the Middle East. However, its origins are far older, with evidence of its use spanning millennia across diverse civilizations.
In ancient Egypt, turquoise was a symbol of royalty and power, adorning the pharaohs and other rulers. Chinese artisans were carving it into intricate objects more than 3,000 years ago. For Native American cultures, particularly the Apache, turquoise held profound spiritual significance; it was believed that the gem could be found by following a rainbow to its end. Across various traditions, turquoise was attributed with protective and beneficial powers. From the 13th century onward, European lore held that the stone could guarantee health, good fortune, and protection against falls, particularly from horses. Some beliefs suggested the gem would shatter as a warning of impending disaster. Hindu mystics believed that seeing turquoise after the new moon ensured immense wealth. In literature, Shakespeare referenced the stone’s association with affection in The Merchant of Venice, where a turquoise ring symbolizes a hope for love.
Geologically, turquoise forms in arid, semi-arid environments where groundwater leaches chemicals from adjacent rocks. The presence of copper imparts its characteristic sky-blue color, while iron can lend a greenish tint. It is a relatively soft gemstone, with a Mohs hardness ranging from 5 to 6, making it susceptible to scratching and breaking. It is also sensitive to chemicals, oils, and pigments, which can discolor the stone. To enhance its durability and color, turquoise is commonly stabilized—a process where the stone is impregnated with a clear resin or wax. This treatment is standard in the industry and helps protect the gem from environmental damage. Due to its softness and sensitivity, turquoise is best suited for jewelry that is not subjected to daily wear and tear, such as earrings, pendants, and beads.
Tanzanite: The Modern Marvel of Tanzania
In stark contrast to the ancient history of turquoise, tanzanite is a distinctly modern gemstone, its discovery and rise to prominence occurring within the last century. First identified in 1967 in the Merelani Hills of northern Tanzania, this variety of the mineral zoisite was initially found in its natural brownish state. The gem’s vivid blue to violet hues are the result of heat treatment, a process that permanently alters its color and is now considered a standard industry practice. The heat-treated color is stable and does not introduce additional durability concerns.
Tanzanite’s story is inextricably linked to the legendary jewelry company Tiffany & Co., which recognized its potential and became its primary distributor following its discovery. In 1968, Tiffany launched a major advertising campaign, promoting tanzanite as a rare and beautiful new gem. Its captivating color, high clarity, and ability to be cut into large, impressive stones quickly made it a sensation. The gem’s rapid ascent in popularity led to its designation as a birthstone for December in 2002, and it is also the gemstone for the 24th wedding anniversary.
The geographical origin of tanzanite is as unique as its story. The Merelani Hills are the only location on Earth where tanzanite is mined commercially. The landscape is characterized by grass-covered hillsides and rocky soil, with the snow-capped peak of Mount Kilimanjaro looming in the distance. Mining operations are extensive, with workers excavating mines over 100 meters deep into the earth to recover the rough material. This extreme rarity contributes significantly to tanzanite’s value; it is considered the most valuable of the December birthstones due to its limited geographic source.
In terms of durability, tanzanite sits at 6 to 7 on the Mohs scale of hardness. While it is resistant to the effects of normal heat, light, and common chemicals, it is prone to chipping and abrasion due to its cleavage. It can also be attacked by hydrochloric and hydrofluoric acids. For these reasons, tanzanite is best set in protective jewelry styles such as earrings and pendants, rather than in rings that might experience sharp impacts. Cleaning should be gentle, using only warm, soapy water and avoiding ultrasonic cleaners or steam.
Zircon: The Sparkling and Durable Gem
Zircon is one of the oldest minerals on Earth, with crystals dating back billions of years, yet it remains a popular and brilliant choice for December. The blue variety of zircon, which is the most common for birthstone purposes, is typically achieved through heat treatment of brown or reddish-brown zircon crystals. This process creates a stable, bright blue color that can range from pale to intense. Zircon is prized for its exceptional brilliance and fire, which often surpasses that of many other gemstones, including diamond. Its high refractive index and strong dispersion give it a sparkling quality that makes it highly desirable in jewelry.
Historically, zircon has been confused with other gems, most notably cubic zirconia (a synthetic diamond simulant), which has led to some misconceptions about its value. However, natural zircon is a distinct and valuable gemstone. As a birthstone, zircon is associated with clarity, wisdom, and a sense of balance. Its journey onto the official birthstone list occurred in 1952, when the Jewelry Industry Council of America added it to December’s offerings, providing a more durable blue option alongside turquoise.
Zircon is sourced from several locations worldwide, including Sri Lanka, Cambodia, and Australia. It has a Mohs hardness of 6.5 to 7.5, making it relatively durable, though it can be brittle along its edges. Care should be taken to avoid sharp blows and exposure to extreme heat or sudden temperature changes, which can cause cracking. It is also recommended to avoid ultrasonic cleaners and steam for cleaning zircon jewelry. Its durability makes it suitable for a variety of jewelry settings, including earrings, pendants, and protected rings, where its sparkle can be fully appreciated.
Blue Topaz: The Icy and Durable Choice
Blue topaz, with its clear, icy blue hues, is a gemstone of remarkable durability and accessibility. While the exact historical origin of blue topaz is unknown, it has been found and used throughout history. Today, it is mined in several countries, including Sri Lanka, Brazil, Mexico, Nigeria, and the United States, where it is recognized as the official state gem of Texas. This wide geographic distribution contributes to its affordability compared to rarer gems like tanzanite.
Blue topaz is notable for being the hardest and most durable of the December birthstones. On the Mohs hardness scale, it registers an 8, making it highly resistant to scratching and suitable for everyday wear, including in rings. This durability, combined with its attractive color and clarity, makes blue topaz an excellent choice for those seeking a low-maintenance, long-lasting piece of jewelry. Its color is typically enhanced through irradiation and heat treatment, a standard process that produces the stable, vivid blues seen in the market.
As a birthstone, blue topaz is valued for its beauty and practicality. While it is not listed in the traditional trio of turquoise, zircon, and tanzanite, its inclusion in many modern birthstone lists for December speaks to its popularity. It offers a cool, serene blue that complements the winter season. In terms of care, blue topaz is relatively low-maintenance. It can be cleaned with warm, soapy water and a soft brush. While it is sensitive to sharp impacts, its hardness makes it resilient for most jewelry applications. Its combination of durability, sparkle, and affordability has secured its place as a beloved modern gemstone.
Comparative Properties and Care
The four December birthstones offer a spectrum of colors, durability, and care requirements, summarized in the table below. This comparison highlights the practical considerations for selecting and maintaining each gem.
| Property | Tanzanite | Turquoise | Zircon | Blue Topaz |
|---|---|---|---|---|
| Natural Color | Blue to violet | Sky blue to greenish | Blue | Pale blue to dark blue |
| Heat Treatment | Common | Stabilization common | Common | Common |
| Mohs Hardness | 6 to 7 | 5 to 6 | 6.5 to 7.5 | 8 |
| Best For | Occasional rings, earrings, pendants | Earrings, pendants, beads | Earrings, pendants, protected rings | Daily wear rings, all jewelry |
| Sensitivity | Prone to chipping | Sensitive to chemicals and moisture | Brittle at edges | Sensitive to sharp impacts |
| Geographic Origin | Tanzania only | Worldwide | Sri Lanka, Cambodia, Australia | Worldwide |
| Care Needs | Gentle cleaning only | Very gentle, avoid all chemicals | Avoid steam and ultrasonic | Mild care, avoid sharp hits |
This table underscores the diversity within the December birthstone family. For those who prioritize durability and daily wear, blue topaz is the clear choice. Zircon offers a balance of brilliance and moderate durability, ideal for protected settings. Tanzanite provides a unique, shifting color and rarity but requires careful handling. Turquoise, with its deep historical and cultural roots, offers a soft, earthy aesthetic but demands the most gentle care. The choice ultimately depends on the wearer’s lifestyle, aesthetic preference, and the symbolic meaning they wish to carry.
Conclusion
The birthstones of December—turquoise, tanzanite, zircon, and blue topaz—collectively embody the cool, tranquil essence of winter through their blue coloration. Each stone tells a distinct story: turquoise, an ancient talisman of protection and good fortune; tanzanite, a modern marvel of rare beauty from a single source in Tanzania; zircon, an ancient mineral of brilliant sparkle and durability; and blue topaz, a hard and accessible gem of icy clarity. Their inclusion on the birthstone list reflects both historical tradition and the evolving nature of the gem trade, offering a wide array of choices for personal expression. Whether chosen for its historical significance, metaphysical properties, or simply its captivating color, a December birthstone serves as a timeless and meaningful connection to the month and the season.