December is unique in the calendar of birthstones, offering not one but four distinct gemstones for those born in its final month. This abundance provides a cool, wintry palette of blues and violets, ranging from the historic charm of turquoise to the modern brilliance of blue topaz. The four recognized December birthstones are Turquoise, Zircon, Tanzanite, and Blue Topaz. Each stone carries its own geological history, gemological profile, and cultural significance, giving December-born individuals a wealth of choice. This article explores the origins, properties, symbolism, and care requirements of each gemstone, drawing on established gemological knowledge and historical lore.
The modern list of birthstones, largely standardized by the American Gem Society and the Jewelers of America, includes these four gems for December. While turquoise is the traditional and historic birthstone for the month, zircon, tanzanite, and blue topaz have been added over time to reflect contemporary tastes and market availability. This comprehensive guide will delve into the story of each stone, helping enthusiasts, buyers, and students understand the unique characteristics that make each one a worthy emblem for the last month of the year.
Turquoise: The Ancient Protector
History and Lore
Turquoise is one of the oldest known gemstones in human history, with its use dating back thousands of years. Its name is derived from the French pierre turquoise, meaning "Turkish stone," as it was brought to Europe from the mines of Persia (modern-day Iran) through Turkish trade routes. Historical sources indicate that turquoise was a favored gem for amulets, prized for its relative ease in cutting and shaping for inscriptions. It was believed to possess protective powers, warding off danger and bringing good fortune. Ancient cultures, including the Egyptians, Persians, and Native Americans, held turquoise in high regard. For instance, King Tutankhamun was buried with a turquoise bracelet, and the stone was used in elaborate jewelry and funerary masks.
The stone’s lore extends to its use as a barometer for the wearer’s health. It was believed that turquoise could warn of approaching illness or danger by becoming pale or changing color. In Tibetan culture, turquoise was considered a birthstone of fortune, health, and success, and was even used as a currency. The Incas and Mayas offered turquoise as a gift to their gods, while Native Americans of the Southwest associated the stone with youth and strength. Beyond its protective qualities, turquoise was also prized by lovers and married couples as a gemstone that could preserve relationships and friendship if given as a gift.
Geological Formation and Sources
Turquoise is an opaque, blue-to-green mineral composed of hydrated copper and aluminum phosphate. Its distinctive color comes from copper, while traces of iron can shift the hue toward green. The gem forms in arid regions where copper-rich groundwater reacts with aluminum-bearing minerals in rocks. This process typically occurs in areas with specific geological and weather conditions, often in volcanic or sedimentary rock formations.
Significant sources of turquoise include the southwestern United States (notably Arizona, New Mexico, and Nevada), Iran, Egypt, China, Mexico, and parts of Central Asia and Africa. The stone often contains a "matrix," which is a web of host rock material (such as limonite or iron oxide) that remains within the turquoise, creating unique patterns. This matrix can add to the stone's character, with some varieties like spiderweb turquoise being highly sought after for their intricate designs.
Gemological Properties
Turquoise is valued for its distinctive color and opaque nature, which makes it ideal for cabochon cuts. It is a relatively soft gemstone, with a Mohs hardness of 5 to 6. This softness means it can be scratched or damaged by everyday wear, making it more suitable for jewelry that is handled with care, such as pendants or earrings, rather than rings that are subject to frequent impact. It has a specific gravity of 2.6 to 2.9 and is typically cut into smooth, rounded shapes to highlight its color and matrix. The stone's durability is moderate, and it is sensitive to chemicals, heat, and sudden temperature changes, which can cause cracking or discoloration.
Symbolism and Metaphysical Beliefs
Turquoise is deeply symbolic, representing protection, wisdom, tranquility, and friendship. It is often seen as a steadying force, offering grounding and calm during times of chaos. In metaphysical traditions, turquoise is believed to align with the throat chakra, enhancing communication and self-expression. It is also associated with emotional balance and spiritual protection, making it a popular choice for those seeking a sense of security and peace.
Care and Cleaning
Due to its moderate hardness and porosity, turquoise requires careful maintenance. It should be cleaned with a soft, damp cloth and mild soap, avoiding ultrasonic cleaners, steam, and harsh chemicals. Store turquoise jewelry separately to prevent scratching, and avoid exposing it to direct sunlight or extreme temperatures for prolonged periods, as this can fade its color. With proper care, turquoise jewelry can remain beautiful for generations.
Zircon: The Sparkling Traditionalist
History and Lore
Zircon is one of the traditional birthstones for December, with a history that dates back centuries. It is often confused with cubic zirconia, a synthetic material, but natural zircon is a distinct and valuable gemstone. Historically, zircon was believed to promote prosperity and honor. Its name may be derived from the Arabic zargun, meaning "gold-colored," though it is most prized for its brilliant blue hue in the context of December birthstones. Blue zircon, in particular, has been associated with clarity, wisdom, and a sense of balance. It is said to sharpen focus and boost mental clarity, making it a stone for those seeking insight and truth.
Geological Formation and Sources
Zircon is a mineral belonging to the nesosilicate group, with a chemical formula of ZrSiO₄. It forms in igneous and metamorphic rocks, often as small, prismatic crystals. Blue zircon is typically produced by heat-treating brown zircon crystals to remove the brown coloration and enhance the blue tones. This treatment is common and widely accepted in the gem trade.
Major sources of zircon include Cambodia, Thailand, Sri Lanka, and Australia. Australian zircon, in particular, is known for its high quality. The gem is mined from alluvial deposits, where it has been weathered from its host rock and concentrated in riverbeds and coastal areas. Zircon is also found in some parts of the United States, though the blue variety is less common.
Gemological Properties
Zircon is one of the hardest and most durable gemstones among the December options, with a Mohs hardness of 6.5 to 7.5. This makes it more suitable for daily wear compared to turquoise or tanzanite. It has a high refractive index (1.92 to 2.01) and strong dispersion (0.039), giving it exceptional brilliance and fire—often compared to diamonds. Zircon is typically faceted to maximize its sparkle, and it can be cut into various shapes, including rounds, ovals, and emeralds. The stone has a specific gravity of 4.6 to 4.7 and is doubly refractive, which can sometimes cause doubling of facet edges under magnification. Blue zircon is often a light to medium blue, though it can be darker with proper treatment.
Symbolism and Metaphysical Beliefs
Zircon is associated with clarity, wisdom, and mental focus. It is believed to help clear the mind of distractions and enhance spiritual growth. In some traditions, zircon is thought to attract prosperity and honor, making it a popular stone for those seeking success and recognition. Its bright, clear appearance is said to reflect inner truth and integrity.
Care and Cleaning
With its good hardness, zircon is relatively durable for jewelry. However, it can be brittle and prone to chipping if struck hard. It should be cleaned with warm, soapy water and a soft brush, avoiding ultrasonic cleaners and sudden temperature changes. Store zircon jewelry separately to prevent scratching from harder gems like diamonds.
Tanzanite: The Modern Marvel
History and Lore
Tanzanite is a relatively new gemstone in the world of fine jewelry, discovered in the 1960s in Tanzania. It was quickly recognized for its unique violet-blue color and has since become a popular alternative birthstone for December. Tanzanite is associated with transformation, new beginnings, and fresh chapters in life. Its shifting blue-violet hues are said to reflect the feeling of stepping into something new with clarity and curiosity. While it lacks the ancient history of turquoise or zircon, tanzanite has rapidly accumulated its own lore, symbolizing elegance, modernity, and spiritual awakening.
Geological Formation and Sources
Tanzanite is a variety of the mineral zoisite, with the chemical formula Ca₂Al₃(SiO₄)₃(OH). Its striking color is due to the presence of vanadium, which causes a blue to violet hue. The gem is found exclusively in a small area near Mount Kilimanjaro in Tanzania, making it one of the rarest gemstones on earth. This single-source location adds to its value and allure. Tanzanite forms in metamorphic rocks under specific geological conditions, and its deposits are limited, which contributes to its rarity and potential future scarcity.
Gemological Properties
Tanzanite has a Mohs hardness of 6.5 to 7, making it moderately durable but softer than zircon or topaz. It is typically cut into faceted gems to enhance its color and brilliance, though it is often used in cabochon forms for jewelry that highlights its unique hue. The stone exhibits strong trichroism, meaning it can show three different colors (blue, violet, and burgundy) depending on the viewing angle. This property requires skilled cutting to orient the gem for the best color display. Tanzanite has a specific gravity of 3.35 to 3.38 and is often heated to improve color stability and remove brownish tones. Most tanzanite on the market has been heat-treated, a standard and accepted practice.
Symbolism and Metaphysical Beliefs
Tanzanite is deeply symbolic of transformation and personal growth. It is believed to facilitate spiritual awareness, enhance intuition, and promote a sense of calm and balance. Its color is often associated with the throat and third eye chakras, aiding in communication and inner vision. For those born in December, tanzanite represents a journey of change and self-discovery.
Care and Cleaning
Tanzanite requires careful handling due to its moderate hardness and potential for cleavage. It should be cleaned with warm, soapy water and a soft cloth, avoiding ultrasonic cleaners, steam, and harsh chemicals. Protect tanzanite jewelry from hard impacts and sudden temperature changes. It is best suited for pendants, earrings, and occasional-wear rings rather than daily-wear rings.
Blue Topaz: The Modern Classic
History and Lore
Blue topaz is a modern addition to the December birthstone list, gaining popularity in the late 20th century. While topaz as a mineral has been known for centuries, blue topaz is typically created through the irradiation and heat treatment of colorless topaz. This process allows for the production of large, vibrant blue stones that are affordable and widely available. Blue topaz is associated with clarity, communication, and calm. It is often seen as a stone that promotes peaceful expression and emotional balance. Its crisp, icy blue color makes it a favorite for contemporary jewelry designs.
Geological Formation and Sources
Topaz is a silicate mineral with the chemical formula Al₂SiO₄(F,OH)₂. Blue topaz is derived from colorless or pale topaz crystals, which are subjected to irradiation (often with neutrons or gamma rays) followed by heating to achieve a stable blue color. This treatment is permanent and does not affect the stone's durability. Natural blue topaz is extremely rare; almost all blue topaz on the market is treated.
Major sources of topaz include Brazil, Sri Lanka, and the United States (notably Texas and California). The raw material for blue topaz often comes from these regions, but the treatment is typically performed in specialized facilities. The gem is mined from pegmatites and alluvial deposits.
Gemological Properties
Blue topaz has a Mohs hardness of 8, making it one of the hardest and most durable gemstones among the December options. This durability makes it excellent for rings and other jewelry that sees daily wear. It has a refractive index of 1.61 to 1.63 and is typically faceted to maximize its brilliance. Blue topaz comes in a range of blue shades, from light sky blue to deep Swiss blue. The stone is often cut into large sizes, offering good value for its visual impact. It has a specific gravity of 3.49 to 3.57 and is generally eye-clean, meaning it lacks visible inclusions.
Symbolism and Metaphysical Beliefs
Blue topaz is believed to enhance communication, reduce stress, and promote tranquility. It is associated with the throat chakra, aiding in clear and honest expression. Some traditions link blue topaz to creativity and inspiration, making it a stone for artists and writers. Its cool blue color is said to evoke feelings of peace and serenity.
Care and Cleaning
Blue topaz is relatively easy to care for due to its hardness. It can be cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and harsh chemicals, as they may damage the stone or its settings. Store blue topaz jewelry separately to prevent scratches from harder gems. With proper care, blue topaz jewelry can maintain its beauty for many years.
Comparative Summary of Gemological Properties
To provide a clear overview, the following table summarizes the key gemological properties of the four December birthstones, based on the information from the sources. This table helps in comparing durability, color, and suitability for different types of jewelry.
| Gemstone | Mohs Hardness | Chemical Composition | Typical Color | Primary Sources | Treatment Common? |
|---|---|---|---|---|---|
| Turquoise | 5–6 | Hydrated Cu-Al phosphate | Blue to green, often with matrix | USA, Iran, Egypt, China, Mexico | Yes (stabilization) |
| Zircon | 6.5–7.5 | ZrSiO₄ | Blue (from heat-treated brown) | Cambodia, Thailand, Sri Lanka, Australia | Yes (heat) |
| Tanzanite | 6.5–7 | Ca₂Al₃(SiO₄)₃(OH) | Violet-blue, trichroic | Tanzania (exclusive) | Yes (heat) |
| Blue Topaz | 8 | Al₂SiO₄(F,OH)₂ | Light to deep blue | Brazil, Sri Lanka, USA | Yes (irradiation & heat) |
Note: Hardness values are approximate and based on standard gemological references. All listed treatments are common and accepted in the gem trade.
Choosing and Caring for December Birthstone Jewelry
When selecting a December birthstone, consider the intended use and personal preferences. For daily-wear rings, blue topaz and zircon offer the best durability due to their higher hardness. Turquoise and tanzanite are better suited for pendants, earrings, or occasional-wear rings. Color preference also plays a role: turquoise offers a unique matrix pattern, zircon provides exceptional sparkle, tanzanite gives a shifting violet-blue, and blue topaz offers a consistent, crisp blue.
Care requirements vary by stone. All benefit from gentle cleaning with mild soap and water, but avoid ultrasonic cleaners for turquoise, tanzanite, and zircon (due to potential brittleness). Store each piece separately to prevent scratching. For turquoise, avoid exposure to chemicals, perfumes, and prolonged sunlight. For tanzanite and zircon, protect from hard impacts. Blue topaz is the most resilient but still requires basic care to maintain its luster.
When purchasing, ensure you buy from reputable retailers who provide disclosure about treatments and origins. Certificates from gemological laboratories can offer additional assurance, especially for higher-value stones like tanzanite or zircon. Consider the metal setting as well; for example, turquoise often looks striking in silver, while blue topaz and zircon pair well with white gold or platinum.
Conclusion
December's four birthstones—turquoise, zircon, tanzanite, and blue topaz—offer a diverse range of colors, histories, and properties. Turquoise stands as the ancient guardian, rich with lore and protective symbolism. Zircon brings traditional brilliance and durability. Tanzanite, the modern marvel, captivates with its rarity and transformative energy. Blue topaz provides a durable, affordable option with a crisp blue hue. Each stone reflects a different aspect of winter's cool palette, from the earthy matrix of turquoise to the icy sparkle of blue topaz. For those born in December, this variety allows for a personal connection to a gemstone that resonates with their style, values, and lifestyle. By understanding the unique characteristics and care needs of each, enthusiasts can choose and cherish their birthstone for years to come.