The month of December is uniquely associated with not one, but three distinct birthstones: tanzanite, turquoise, and zircon. Each gemstone offers a captivating palette of blues and beyond, providing a diverse range of choices for those born in the final month of the year. This article explores the rich histories, geological origins, gemological properties, and cultural significance of these three remarkable stones, drawing upon authoritative gemological resources to provide a comprehensive guide for enthusiasts, collectors, and jewelry buyers.
History and Lore
Turquoise: An Ancient Treasure
Turquoise is one of the oldest known gemstones, cherished for millennia across numerous civilizations. Its history is deeply woven into the fabric of ancient cultures. The pharaohs and other rulers of ancient Egypt adorned themselves with this vibrant stone, and Chinese artisans were carving it more than 3,000 years ago. The turquoise birthstone was believed to possess many beneficial powers, such as guaranteeing health and good fortune. This belief in its protective qualities is a common thread throughout its history. In Tibetan culture, turquoise is considered a national treasure, believed to grant health, good fortune, and protection from evil, while also imparting peace to the wearer. Among the Pueblo people, the stone was thought to have derived its color from the sky, while the Hopi believed it was produced by lizards scurrying over the earth. Turquoise also holds a place in royalty and modern history; it adorns the funerary mask of King Tut, who ruled Egypt over 3,000 years ago, and was worn by Wallis Simpson, Duchess of Windsor, in a famous necklace by Cartier. In European tradition, the gift of a turquoise ring signifies "forget me not," and it is the gem of the 11th wedding anniversary.
Tanzanite: A Modern Discovery
In contrast to turquoise's ancient lineage, tanzanite is a relative newcomer to the world of colored stones, yet it is considered one of the most exciting gem discoveries of the 20th century. Its story began in 1962 when blue stones emerging from Tanzania were identified as the mineral zoisite. However, the primary source for this December birthstone was not located until 1967, when prospectors found it in the Merelani Hills. The stone was eventually named tanzanite in honor of its country of origin. Tiffany & Co. recognized its international appeal and became its main distributor, helping to propel it to global fame. The tanzanite birthstone is often described as "velvety," a term that captures the depth and saturation of its color, which ranges from a pure rich blue to violet. The blue hue is considered the most valuable.
Zircon: The Rainbow Gem
Zircon, the third December birthstone, is often confused with cubic zirconia, a synthetic diamond simulant, but it is a naturally occurring gemstone with a long history. While the provided sources do not offer extensive historical lore for zircon, they highlight its remarkable range of colors. Zircon is known for its rainbow varieties, offering shades of bright red, yellow, green, purple, and brown, in addition to its blue varieties. This diversity of color provides a wide spectrum of choices for those seeking a December birthstone that reflects their personal style and personality.
Geological Formation and Sources
Turquoise
Turquoise is a semi-translucent to opaque gem that ranges from blue to green. A distinctive characteristic of the stone is the presence of veins of matrix—remnants of the rock in which it formed—running through it. The most significant and historically important source for turquoise is the Nishapur district of Iran, where the stone has been mined for over 1,000 years.
Tanzanite
Tanzanite's geological story is confined to a very small area in northern Tanzania. The primary source is the Merelani Hills, a landscape of grass-covered hillsides, scrub brush, and rocky soil. The mining operations here are extensive and mechanized, with workers recovering tanzanite from mines dug over 100 meters (more than 300 feet) deep into the earth. This specific geographic location is the only known commercial source of tanzanite in the world.
Zircon
The provided sources do not specify the geological formation or primary mining locations for zircon. Therefore, based on the available information, this aspect of the gemstone cannot be detailed further.
Gemological Properties
The three December birthstones possess distinct physical and chemical properties that define their durability, appearance, and care requirements. Understanding these properties is essential for proper selection and maintenance.
Turquoise is an opaque gem, meaning light does not pass through it. It is relatively soft compared to other gemstones, which makes it susceptible to scratching and damage. Its chemical composition is complex and varies, which contributes to its sensitivity to environmental factors.
Tanzanite is a member of the zoisite mineral family. It is a pleochroic gem, meaning it shows different colors when viewed from different crystal directions. This is why it can display shifting shades of blue and violet depending on the light. Its hardness on the Mohs scale is between 6 and 7, making it moderately durable but softer than many other popular gems like sapphire or diamond. Most tanzanite on the market is heat-treated to transform brownish zoisite into the desirable blue-violet hues; this treatment is permanent.
Zircon is known for its high brilliance and fire, which can rival that of diamond. It is relatively hard, scoring 6.5 to 7.5 on the Mohs scale, making it more durable than tanzanite and turquoise. However, it is brittle and can abrade or chip if subjected to rough conditions. Zircon is commonly heat-treated to produce blue and colorless varieties, as well as orange, yellow, and red. The color from this treatment is generally stable, though some heat-treated stones may revert to their original colors (usually light brown) after prolonged exposure to bright light.
The following table summarizes the key gemological properties of the three December birthstones based on the provided sources:
| Gemstone | Hardness (Mohs Scale) | Transparency | Common Treatments | Key Property |
|---|---|---|---|---|
| Turquoise | Not specified in sources | Semi-translucent to opaque | Not specified in sources | Often contains matrix veins |
| Tanzanite | 6 to 7 | Transparent to translucent | Heat treatment (to produce blue/violet hues) | Pleochroic (shows blue and violet) |
| Zircon | 6.5 to 7.5 | Transparent | Heat treatment (for blue, colorless, orange, yellow, red) | High brilliance and fire; can abrade |
Symbolism and Metaphysical Beliefs
The symbolism attached to each December birthstone is as varied as the stones themselves.
Turquoise is rich with metaphysical meanings. Across many cultures, it has been treasured for centuries, symbolizing protection, luck, and healing. Its association with health and good fortune is a recurring theme in historical accounts. In Tibet, it is believed to grant these benefits and provide protection from evil. The stone is also said to impart peace to the wearer.
Tanzanite, while a newer addition to the gemstone lexicon, carries its own symbolic weight. It is celebrated for its captivating shades of blue and violet and is said to radiate positivity and truth.
Zircon is associated with wisdom and honesty. Its wide array of colors allows individuals to choose a stone that not only fits the December birthstone tradition but also aligns with personal symbolism and style.
Care and Cleaning
Proper care is crucial for maintaining the beauty and integrity of these gemstones, especially given their varying levels of durability.
Turquoise is particularly sensitive. It can be damaged by acids and discolored by chemicals, cosmetics, skin oils, and perspiration. The safest way to clean turquoise jewelry is with warm, soapy water. It should never be cleaned with steam or ultrasonic cleaners. Heat or solvents can damage the treated surfaces on some turquoise stones.
Tanzanite (hardness 6-7) is resistant to the effects of normal heat, light, and common chemicals. However, it may crack if exposed to very high temperatures or sudden temperature changes, and it abrades easily. It can be attacked by hydrochloric and hydrofluoric acids. Due to its relative softness and tendency to abrade, tanzanite is best set in earrings or pendants rather than in rings or bracelets that are subject to daily wear and impact. For cleaning, use a soft brush and mild soap in warm water. Ultrasonic and steam cleaners are not recommended.
Zircon (hardness 6.5-7.5) is relatively hard but brittle. Because it tends to abrade, it is best to avoid wearing it in rough conditions, such as while gardening, playing sports, or doing dishes. It is generally stable when exposed to light and chemicals, though some heat-treated colors may fade with prolonged bright light exposure. Cleaning should be done with a soft brush and mild soap in warm water. Ultrasonic and steam cleaners are not recommended for zircon.
Conclusion
The December birthstones—tanzanite, turquoise, and zircon—offer a remarkable trio of choices, each with a unique identity. Turquoise connects the wearer to millennia of human history and cultural symbolism, from ancient Egypt to Tibet. Tanzanite represents the excitement of modern discovery, with its velvety, shifting hues mined from a single source in Tanzania. Zircon provides a spectrum of colors and exceptional brilliance, though it requires careful handling due to its brittleness. Together, they embody the diverse beauty of the winter month, offering options for every preference, style, and budget. Whether drawn to the ancient protective lore of turquoise, the vibrant modernity of tanzanite, or the rainbow palette and fire of zircon, those born in December have a rich selection of gemstones to call their own.