December is a month of celebration, reflection, and transition. It marks the end of the calendar year and the arrival of the winter season. Along with its festive connotations, December is also known for having three distinct birthstones: turquoise, tanzanite, and zircon—all of which are celebrated for their beautiful blue hues. These gemstones, each with a rich history and unique properties, have captivated people for centuries, and their symbolism continues to resonate in modern jewelry and gemstone culture. This article explores the origins, characteristics, cultural significance, and care of these December birthstones, offering a comprehensive look at the gems that represent this special month.
Historical & Cultural Significance
December’s association with three birthstones is relatively unusual compared to most months, which typically have a single representative gem. This multiplicity reflects the evolving nature of birthstone lists over time and the diverse cultural and commercial influences that have shaped them.
Historically, December was believed to be the tenth month in the Roman calendar before the Julian and Gregorian reforms. As such, the month's name comes from the Latin word decem, meaning "ten." This historical nuance adds to the richness of December's gemstone legacy.
Early Birthstone Traditions
The earliest known birthstone traditions were rooted in biblical references, particularly the High Priest’s breastplate described in the Book of Exodus, which was said to contain twelve gemstones representing the twelve tribes of Israel. In these early traditions, a red gemstone—likely a ruby—was associated with December.
However, the modern birthstone lists have evolved significantly. The first major shift occurred in 1870, when Tiffany & Co. listed turquoise as the December birthstone in their "Gregorian Birthstone Poems" pamphlet. This was followed in 1912 by the National Association of Jewellers (now the Jewellers of America), which added lapis lazuli as an alternative to turquoise. By 1952, zircon was included in the list by the Jewelry Industry Council of America, and in 2002, tanzanite was added to the December birthstone lineup, completing the trio we recognize today.
The inclusion of these stones reflects not only historical and cultural traditions but also commercial interests and gemological discoveries. For example, tanzanite, discovered in 1967, is a modern gemstone that quickly gained popularity due to its striking blue-violet hues and its exclusive origin in Tanzania.
Symbolism and Meaning
Each of December’s birthstones carries unique symbolic meanings that have been passed down through generations.
Turquoise has been cherished for thousands of years and is one of the oldest known gemstones. Ancient civilizations, including the Egyptians and Chinese, valued turquoise for its protective and healing properties. It was believed to promote health, good fortune, and spiritual clarity. In some cultures, turquoise was thought to protect the wearer from danger, particularly when riding horses.
Tanzanite, although a relatively recent discovery, is associated with transformation, spiritual awakening, and emotional healing. Its deep blue-violet color is said to activate the throat, third-eye, and crown chakras, enabling the wearer to connect with higher dimensions and enhance their psychic abilities. It is also believed to offer protection and promote self-transformation.
Zircon, particularly in its blue form, has been used in jewelry for centuries. It is known for its brilliance and fiery luster. Historically, zircon was believed to offer protection from harm and was associated with divine favor. In medieval times, zircon was thought to enhance dream interpretation and was sometimes called the “chameleon of gems” due to its ability to display multiple colors.
These symbolic associations have contributed to the enduring popularity of these gemstones and their continued use in jewelry and spiritual practices.
Geological Formation and Sources
Understanding the geological origins and sources of December’s birthstones helps to appreciate their rarity and beauty.
Turquoise
Turquoise is a phosphate mineral that forms in the oxidation zones of copper deposits. It is typically found in limestone or volcanic rocks where water has transported and concentrated the minerals. The formation of turquoise is a relatively slow process, often taking thousands of years. The gemstone is usually semi-translucent to opaque and can range in color from deep blue to green, depending on the amount of copper and aluminum present. Matrix—the web-like patterns formed by the surrounding rock—can also influence the appearance of turquoise.
Major sources of turquoise include Nepal, China, Iran, Egypt, the United States (particularly Nevada and Arizona), and Mexico. Among these, Nepal and Iran are known for producing high-quality turquoise with rich blue coloration and minimal matrix.
Tanzanite
Tanzanite is a trigonal mineral that forms under specific geological conditions. It is a variety of zoisite, and its striking blue-violet color is due to trace amounts of vanadium and chromium. Tanzanite is only found in Tanzania, specifically in the Merelani Hills, near the city of Arusha. The gemstone forms in metamorphic rocks, particularly in areas where calcium-rich fluids have interacted with other minerals.
The Merelani Hills are the sole source of tanzanite, making it one of the rarest gemstones in the world. The gem is typically treated with heat to enhance its color, and this process is essential to bring out the vivid blue-violet hues that define tanzanite.
Zircon
Zircon is a zirconium silicate that occurs in a wide range of colors, including blue, colorless, red, yellow, and green. The blue variety, known as cubic zirconia when synthesized, is the most popular in jewelry. Natural zircon is often heat-treated to produce the blue and colorless varieties. Zircon is found in igneous rocks and is commonly associated with sapphire deposits. Major sources include Sri Lanka, Australia, Myanmar, Vietnam, and Cambodia.
Zircon is a hard gemstone, ranging from 6 to 7.5 on the Mohs scale, which makes it suitable for use in jewelry. However, due to its brittle nature, it requires careful handling and cleaning to avoid damage.
Gemological Properties
Each of December’s birthstones has distinct gemological properties that influence its appearance, durability, and care.
| Gemstone | Color | Hardness (Mohs) | Chemical Formula | Luster | Transparency |
|---|---|---|---|---|---|
| Turquoise | Blue to green | 5–6 | CuAl₆(PO₄)₄(OH)₈·4H₂O | Waxy to greasy | Opaque to semi-translucent |
| Tanzanite | Blue to violet | 6–7 | Ca₂Al₃(SiO₄)₃(OH) | Vitreous | Transparent to translucent |
| Zircon | Blue, colorless, red, etc. | 6–7.5 | ZrSiO₄ | Vitreous | Transparent to translucent |
Turquoise
Turquoise is relatively soft compared to other gemstones, with a hardness of 5–6 on the Mohs scale. It is also porous and sensitive to chemicals and heat, which can cause it to fade or become brittle. Because of this, turquoise is often sealed with a resin or wax to protect it and enhance its durability.
Turquoise is opaque to semi-translucent, with irregular inclusions known as matrix, which can range from black, brown, or white. The presence of matrix can affect the value and appearance of turquoise. High-quality turquoise is typically deep blue with minimal matrix.
Tanzanite
Tanzanite is a relatively durable gemstone, with a hardness of 6–7 on the Mohs scale. It is stable under normal conditions but can be affected by prolonged exposure to light, which may cause it to fade or change color. Tanzanite is typically transparent to translucent and has a vitreous luster. The gemstone is heat-sensitive, and excessive heat can cause it to revert to its natural brownish color.
Tanzanite is not resistant to high acidity or alkaline solutions, so it should be avoided when using harsh chemicals for cleaning. It is also not recommended for use in ultrasonic or steam cleaners.
Zircon
Zircon is a hard and durable gemstone, with a hardness of 6–7.5 on the Mohs scale. It is heat-sensitive, and some varieties may change color when exposed to high temperatures. Zircon is also brittle, so it should be handled with care to avoid chipping or breaking.
Zircon is transparent to translucent and has a high refractive index, giving it a sparkling, fire-like appearance. The gemstone is available in a wide range of colors, including blue, colorless, yellow, red, and green, with the blue variety being the most popular for use in jewelry.
Care and Maintenance
Proper care is essential to maintaining the beauty and longevity of December’s birthstones.
Turquoise
Because of its porosity and sensitivity to chemicals, turquoise should be cleaned gently. Use a soft cloth and mild soap with warm water to wipe the gemstone. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, as these can damage the stone or cause it to lose its color.
Store turquoise in a cool, dry place, away from direct sunlight and other gemstones that could scratch it. If the gemstone is sealed, it should still be handled with care, as the sealant can deteriorate over time.
Tanzanite
Tanzanite should be cleaned with a soft brush and mild soap in warm water. Avoid using ultrasonic or steam cleaners, as they can damage the gemstone. Tanzanite should also be stored in a cool, dark place, as prolonged exposure to light can cause it to fade or change color.
Because tanzanite is heat-sensitive, it should be avoided when exposed to high temperatures, such as when wearing it during physical activities or when using it near heat sources.
Zircon
Zircon should be cleaned with a soft brush and mild soap in warm water. Avoid using ultrasonic or steam cleaners, as they can damage the gemstone. Zircon is brittle, so it should be handled with care to avoid chipping or breaking.
Store zircon in a soft pouch or separate compartment, away from other gemstones that could scratch it. Avoid exposing it to high heat, as this can alter its color.
Conclusion
December’s birthstones—turquoise, tanzanite, and zircon—represent a fascinating blend of history, geology, and symbolism. Each gemstone has a unique origin, color, and set of properties that make it distinct and valuable. From the ancient traditions surrounding turquoise to the modern discovery and popularity of tanzanite, and the brilliant luster of zircon, these stones offer a rich tapestry of meaning and beauty.
Whether you are choosing a birthstone for yourself or a loved one, or simply appreciating the history and properties of these gems, December’s birthstones continue to capture the imagination and admiration of gemstone enthusiasts around the world.