December, the final month of the year, is celebrated not only for its festive holidays but also for its rich collection of birthstones. Unlike many months, December is unique in that it is associated with multiple gemstones—each with its own distinct beauty, history, and symbolism. These gemstones include blue zircon, tanzanite, and turquoise, with lapis lazuli and blue topaz also historically recognized as December birthstones. Together, these gems reflect the spirit of winter—its chill, its brilliance, and its cultural significance across time and geography.
This article delves into the history, properties, and cultural meanings of these December birthstones, offering a comprehensive overview for gemstone enthusiasts, jewelry buyers, and students of gemology. From ancient civilizations that revered these stones for their wisdom and protection to modern jewelry designs that showcase their vibrant hues, the December birthstones continue to captivate and inspire.
History and Lore
The concept of birthstones dates back thousands of years, with the earliest records found in the Bible’s Book of Exodus, which lists 12 gemstones for the breastplate of Aaron, the high priest. These stones were believed to represent the 12 tribes of Israel and were used for spiritual guidance. Over time, the idea of assigning gemstones to specific months evolved, and by the 18th century, a more structured system had developed.
December, in particular, has a dynamic and evolving list of birthstones. In 1870, turquoise was designated as the sole December birthstone in a publication by Tiffany & Co. By 1912, the National Association of Jewellers (now known as the American Gem Trade Association) listed both turquoise and lapis lazuli as December’s stones. In 1952, zircon was added, and in 2002, tanzanite joined the list. This progression reflects the changing tastes and availability of gemstones, as well as the desire to offer a variety of options for December-born individuals.
The inclusion of multiple birthstones for December is not merely for aesthetic variety—it also serves practical purposes. Different gemstones vary in hardness, durability, and availability, allowing people to choose a stone that fits their lifestyle and preferences. For example, tanzanite is a relatively modern gemstone, discovered in 1967 in Tanzania, and is prized for its rarity and vibrant blue-violet color. Meanwhile, turquoise has been used for centuries in jewelry and ceremonial artifacts by ancient cultures in the Middle East, Central Asia, and the Americas.
The December birthstones also carry rich symbolic meanings. Lapis lazuli, for instance, has been associated with wisdom and truth in ancient civilizations such as Egypt and Mesopotamia. It was often used in royal regalia and was believed to enhance intellectual abilities and spiritual insight. Turquoise, on the other hand, has long been considered a stone of protection and good fortune, particularly in Native American and Chinese cultures. It was often carved into amulets and inlaid into jewelry to ward off evil spirits and bring prosperity.
Geological Formation and Sources
The geological origins and sources of the December birthstones are as diverse as their histories. Each gemstone forms under unique conditions and is found in specific regions of the world.
Blue Zircon
Blue zircon is a variety of the mineral zircon, which is composed of zirconium silicate (ZrSiO₄). Zircon is one of the oldest minerals on Earth, with some zircon crystals found in Australia dating back over 4 billion years. The blue color in zircon is typically the result of heat treatment, which alters the crystal structure and enhances its color. This process is permanent and safe, making blue zircon a popular and affordable gemstone.
Zircon is found in various parts of the world, including Australia, Madagascar, Brazil, and Vietnam. The gemstone is known for its high refractive index, which gives it a brilliant sparkle, and its range of colors, from colorless to red, green, and blue. Blue zircon is particularly valued for its fire and brilliance, making it a favorite for jewelry.
Tanzanite
Tanzanite is a relatively new gemstone, first discovered in 1967 in Merelani Hills, near Mount Kilimanjaro in Tanzania. It is a trichroic gemstone, meaning it can display three different colors—blue, violet, and brown—depending on the angle of light. Tanzanite is a variety of cushanite, which is a type of zoisite. The blue to violet color is achieved through heat treatment, which removes the brown color and enhances the blue hues. This treatment is stable and does not affect the gemstone’s durability.
Tanzanite is only found in Tanzania, making it one of the rarest gemstones in the world. Its scarcity and vibrant color have contributed to its popularity, especially in the 21st century. Tanzanite is often used in statement jewelry, such as rings, pendants, and earrings, due to its striking appearance.
Turquoise
Turquoise is a phosphate mineral, with the chemical formula CuAl₆(PO₄)₄(OH)₈·4H₂O. It forms in hydrothermal veins and weathered deposits of copper-bearing rocks. Turquoise is known for its blue-green color, which is caused by the presence of copper ions. The intensity of the blue can vary depending on the amount of copper and the presence of other minerals such as iron and aluminum.
The most famous sources of turquoise are in the United States, particularly in Arizona, New Mexico, and Nevada. Other notable sources include China, Iran, and Egypt, where turquoise has been used for thousands of years. In ancient Egypt, turquoise was used in jewelry and inlay work, and it was often associated with the gods and the afterlife.
Turquoise is a soft gemstone, with a Mohs hardness of 5 to 6, making it more delicate than many other gemstones. It is also porous, which means it can absorb oils and chemicals, so it requires special care when worn or stored.
Lapis Lazuli
Lapis lazuli is a metamorphic rock composed mainly of lazurite, with inclusions of pyrite, calcite, and other minerals. The deep blue color of lapis lazuli is due to the sulfur content in lazurite. The presence of pyrite gives the stone a golden sparkle, which is highly valued in jewelry and decorative objects.
Lapis lazuli is primarily found in Afghanistan, where it has been mined for over 6,000 years. It is also found in Russia, Egypt, and Chile, but Afghanistan remains the most important source. Lapis lazuli has been used in jewelry, carvings, and pigments since ancient times. It was particularly prized in Ancient Egypt, where it was used in masks, amulets, and inlay work.
Lapis lazuli is not typically cut into gemstones but is often polished and shaped into cabochons or used in inlay and mosaics. It is a soft stone, with a Mohs hardness of 5 to 6, and it is sensitive to acids and solvents, so it should be handled with care.
Blue Topaz
Blue topaz is a variety of the mineral topaz, which has the chemical formula Al₂SiO₄(F,OH)₂. The blue color in topaz is caused by natural irradiation, which can occur in nature or be induced in the lab. The most common blue topaz is known as “Sky Blue” topaz, which is a pale, pastel blue. London blue topaz is a deeper, more intense blue, and Swiss blue topaz is a more vivid blue with a slight greenish tint.
Topaz is found in various parts of the world, including Brazil, Myanmar, India, and the United States. Blue topaz is often treated to enhance its color, and these treatments are stable and permanent. Blue topaz is a hard gemstone, with a Mohs hardness of 8, making it durable and suitable for everyday wear in rings, bracelets, and earrings.
Gemological Properties
Understanding the gemological properties of each December birthstone is essential for both collectors and jewelry buyers. These properties include hardness, refractive index, chemical composition, and color stability, all of which affect the stone’s durability and appearance.
Blue Zircon
- Hardness: 6.5 to 7.5 on the Mohs scale
- Refractive Index: 1.92 to 2.00
- Chemical Composition: Zirconium silicate (ZrSiO₄)
- Color: Blue (often treated to enhance color)
- Luster: Vitreous
- Transparency: Transparent to translucent
- Inclusions: Common, including twins and needle-like inclusions
Blue zircon is known for its high refractive index, which gives it a brilliant sparkle. It is also known for its fire, or the dispersion of light, which creates a rainbow-like effect. However, blue zircon is susceptible to cleavage, meaning it can break along certain planes if struck with enough force. It should be handled with care and set in protective mountings.
Tanzanite
- Hardness: 6 to 7 on the Mohs scale
- Refractive Index: 1.69 to 1.70
- Chemical Composition: Calcium aluminum silicate (CaAl₆(SiO₄)₃(OH)₈)
- Color: Blue to violet (trichroic)
- Luster: Vitreous
- Transparency: Transparent to translucent
- Inclusions: Common, including two-phase inclusions and fractures
Tanzanite is trichroic, meaning it can display three different colors under different lighting conditions. It is relatively soft, with a Mohs hardness of 6 to 7, and it is sensitive to heat and chemicals. It is also susceptible to cracking if exposed to sudden temperature changes. Tanzanite is often heat-treated to enhance its color, and this treatment is permanent.
Turquoise
- Hardness: 5 to 6 on the Mohs scale
- Refractive Index: 1.61 to 1.65
- Chemical Composition: Copper aluminum phosphate (CuAl₆(PO₄)₄(OH)₈·4H₂O)
- Color: Blue to green, depending on the presence of copper and iron
- Luster: Waxy to greasy
- Transparency: Translucent to opaque
- Inclusions: Common, including matrix patterns and porosity
Turquoise is a soft gemstone and is porous, which makes it susceptible to staining and chemical reactions. It is often treated with resins or waxes to improve its durability and appearance. Turquoise should be cleaned gently with warm, soapy water and should never be exposed to harsh chemicals or heat.
Lapis Lazuli
- Hardness: 5 to 6 on the Mohs scale
- Refractive Index: 1.50 to 1.70
- Chemical Composition: Lazurite (Na,Ca)₈(Al,Si)₆O₂₀(S,SO₄,C₁)₂·H₂O
- Color: Deep blue with gold flecks from pyrite
- Luster: Waxy to greasy
- Transparency: Opaque
- Inclusions: Common, including pyrite, calcite, and other minerals
Lapis lazuli is opaque, meaning it does not allow light to pass through. It is often polished into cabochons or used in inlay and mosaics. It is soft and porous, and it is sensitive to acids and solvents, so it should be handled with care.
Blue Topaz
- Hardness: 8 on the Mohs scale
- Refractive Index: 1.62 to 1.64
- Chemical Composition: Aluminum silicate (Al₂SiO₄(F,OH)₂)
- Color: Blue (often treated to enhance color)
- Luster: Vitreous
- Transparency: Transparent
- Inclusions: Common, including two-phase inclusions and fractures
Blue topaz is a hard gemstone, making it suitable for everyday wear. It is treated with irradiation and heat to enhance its color, and these treatments are permanent. Blue topaz is resistant to wear and tear and is a popular choice for rings, pendants, and earrings.
Symbolism and Metaphysical Beliefs
The December birthstones are not only prized for their beauty but also for their symbolic and metaphysical meanings. These beliefs have been passed down through generations and continue to influence how people view and use these gemstones today.
Blue Zircon
Blue zircon is believed to bring wisdom, clarity, and spiritual insight. It is often used in meditation and healing practices, and it is said to enhance intuition and psychic abilities. In ancient times, zircon was used to ward off negative energy and promote inner peace.
Tanzanite
Tanzanite is associated with emotional healing and transformation. It is believed to help individuals release old patterns and embrace change. Tanzanite is also said to promote inner peace and harmony, making it a popular stone for emotional balance.
Turquoise
Turquoise has long been considered a stone of protection, good fortune, and healing. In Native American cultures, turquoise was believed to ward off evil spirits and bring prosperity. It was also used in ceremonial rituals and as a symbol of health and vitality. In Chinese culture, turquoise was believed to protect against disease and promote longevity.
Lapis Lazuli
Lapis lazuli is associated with wisdom, truth, and enlightenment. It was used by ancient Egyptian royalty to enhance intellectual abilities and spiritual insight. Lapis lazuli is also believed to promote emotional balance and self-awareness, making it a valuable stone for personal growth.
Blue Topaz
Blue topaz is believed to bring calmness, clarity, and emotional stability. It is often used in meditation and healing practices, and it is said to enhance communication and intuition. Blue topaz is also associated with good fortune and protection, making it a popular stone for those seeking balance and harmony.
Care and Cleaning
Proper care and cleaning are essential for maintaining the beauty and longevity of December birthstone jewelry. Each gemstone has different durability, sensitivity, and care requirements, and it is important to follow appropriate cleaning and storage methods.
Blue Zircon
Blue zircon is relatively durable, but it is susceptible to cleavage, meaning it can break along certain planes if struck. It should be cleaned gently with warm, soapy water and a soft cloth. Avoid using ultrasonic or steam cleaners, as these can damage the stone.
Tanzanite
Tanzanite is sensitive to heat, chemicals, and sudden temperature changes, so it should be stored in a cool, dry place. It can be cleaned with warm, soapy water, but avoid using harsh chemicals or abrasive materials. Tanzanite is not recommended for daily wear in rings, but it can be worn in earrings or pendants with proper care.
Turquoise
Turquoise is a soft and porous gemstone, so it should be cleaned gently with a soft cloth and warm, soapy water. Avoid using harsh chemicals or ultrasonic cleaners, as these can damage the stone or remove treatments. Turquoise should be stored in a cool, dry place, away from direct sunlight and heat sources.
Lapis Lazuli
Lapis lazuli is soft and porous, and it is sensitive to acids and solvents. It should be cleaned gently with a soft cloth and warm, soapy water. Avoid using harsh chemicals or abrasive materials, as these can damage the stone or remove inclusions. Lapis lazuli should be stored in a cool, dry place, away from direct sunlight and heat sources.
Blue Topaz
Blue topaz is a hard and durable gemstone, making it suitable for everyday wear. It can be cleaned with warm, soapy water and a soft cloth. Avoid using harsh chemicals or abrasive materials, and store the stone in a cool, dry place to maintain its color and clarity.
Conclusion
The December birthstones—blue zircon, tanzanite, turquoise, lapis lazuli, and blue topaz—offer a rich and diverse selection of gemstones for those born in the final month of the year. Each gemstone carries its own unique history, symbolism, and properties, making them valuable not only for their beauty but also for their cultural and spiritual significance.
From the ancient civilizations that revered lapis lazuli for its wisdom and truth to the modern discovery of tanzanite in the hills of Tanzania, these gemstones have played a significant role in human history and culture. Their vibrant colors and diverse meanings make them perfect for jewelry, personal expression, and spiritual practices.
Whether you are a gemstone enthusiast, a jewelry buyer, or a student of gemology, the December birthstones offer a fascinating glimpse into the interplay of science, history, and culture. By understanding the properties, origins, and symbolism of these gemstones, you can make informed choices when selecting or caring for December birthstone jewelry.