The concept of birthstones—gemstones associated with each month of the year—has captivated people for centuries. These stones are not only beautiful adornments but also carry rich historical and cultural significance. For December and February, the selection of birthstones reflects a fascinating evolution, blending ancient traditions with modern gemological discovery and commercial influence. December is particularly unique among the months because it has multiple birthstone options, primarily featuring a spectrum of blue hues, while February has maintained a singular, consistent gem for centuries. This article provides an in-depth examination of the gemstones associated with these two months, exploring their properties, symbolism, and their journey to becoming modern birthstones, based on an analysis of historical records, gemological data, and cultural lore.
The modern birthstone tradition has roots in ancient civilizations. As early as the 4th century, the "Book of Stones" in the Old Testament is believed to have listed 12 stones corresponding to the 12 tribes of Israel, later associated with the months of the year. Over time, these associations evolved, influenced by cultural shifts, trade, and the discovery of new gemstones. Today, the modern birthstone list includes both traditional and more recent additions, reflecting the dynamic nature of gemology and human fascination with the natural world. For December, the official modern birthstone list has seen several changes since the 20th century, now including turquoise, tanzanite, blue topaz, and blue zircon. In contrast, February's amethyst has retained its status over centuries, a testament to its enduring popularity and symbolic meaning. This article will delve into the specific histories, geological origins, gemological properties, and care requirements for each of these significant birthstones.
History and Lore: The Path to Birthstone Status
The journey of these gemstones into the official birthstone lists is a story of standardization, commerce, and cultural adoption. The modern birthstone lists were largely formalized in the early 20th century. In 1912, the National Association of Jewelers (now the Jewelers of America) standardized the unofficial American birthstones, combining customs with gemstones that would be practical for jewelry companies to sell. This list has been updated periodically to reflect new discoveries and market trends.
For February, the birthstone is amethyst, a gem that has been consistently recognized for its regal purple color. Its inclusion in the birthstone list is a direct continuation of its historical significance, which dates back to ancient times where it was associated with royalty and spirituality. The consistency of amethyst as February's birthstone underscores its long-standing appeal and the stability of its cultural association.
December's list, however, is a more complex tapestry of additions and changes. The traditional birthstones for December, as recognized by historical lists, are turquoise and lapis lazuli. However, the modern list has expanded significantly. In 1952, the Jewelry Industry Council of America updated the list, adding zircon to December’s offerings. The most recent major addition was tanzanite, which was added in 2002. The modern list for December now includes blue zircon, blue topaz, tanzanite, and turquoise, with some sources also listing blue topaz as the official modern birthstone. The reason for this multiplicity is not definitively known, but it is believed to be a combination of offering more affordable options and incorporating newly discovered or popularized gemstones. This evolution demonstrates how birthstone lists are not static but are influenced by gemological discoveries and commercial offerings, providing a wider palette of blue gemstones to suit different tastes and budgets.
Geological Formation and Sources
Each of these birthstones originates from distinct geological processes and is mined in specific regions of the world, which contributes to their rarity and value.
Turquoise
Turquoise is a hydrated phosphate of aluminum and copper, with a chemical formula of CuAl₆(PO₄)₄(OH)₈·4H₂O. It forms in arid regions where copper minerals and aluminum-rich materials interact with water over long periods. This process typically occurs in the upper levels of copper deposits, where the interaction with groundwater creates the distinctive blue-to-green mineral. The color variation, from sky blue to greenish hues, is primarily due to the varying amounts of copper (which produces blue) and iron (which produces green) in its structure. Turquoise is mined in several locations worldwide, including the United States (notably in Arizona and Nevada), Iran, China, and Egypt. Its formation environment makes it a relatively soft and porous stone, which is a critical factor in its care and durability.
Tanzanite
Tanzanite is a variety of the mineral zoisite, prized for its unique violet-blue hue. It is found in only one location on Earth: the Merelani Hills of Tanzania, near the base of Mount Kilimanjaro. This extreme geographic limitation makes tanzanite exceptionally rare. The gemstone formed approximately 585 million years ago when intense heat and pressure altered the original zoisite crystals. The unique blue color is the result of trace amounts of vanadium within the crystal structure. Its discovery in the 1960s and subsequent marketing by Tiffany & Co. catapulted it to international fame, leading to its addition as a modern birthstone in 2002.
Blue Topaz
Blue topaz is a silicate mineral with the chemical formula Al₂SiO₄(F,OH)₂. While natural blue topaz does occur, it is exceptionally rare. The vast majority of blue topaz on the market today is produced through a process of irradiation and heat treatment of colorless or pale topaz crystals. The treatment enhances the stone's color to a range of blues, from pale sky blue to deep Swiss blue. Major sources of topaz (both natural and treated) include Sri Lanka, Brazil, Mexico, Nigeria, and the United States. In the U.S., topaz is the official state gem of Texas. Its hardness and durability make it a popular choice for jewelry.
Blue Zircon
Zircon is a zirconium silicate mineral (ZrSiO₄) and is one of the oldest minerals on Earth, with some crystals dating back over 4 billion years. Natural blue zircon is rare; most blue zircon on the market has been heat-treated to achieve its color. The gem is found in various locations, including Cambodia, Sri Lanka, Thailand, and Australia. Blue zircon is known for its high brilliance and fire, which can rival that of diamond. Its addition to the December birthstone list in 1952 provided a durable and sparkling blue option.
Amethyst
Amethyst is a variety of quartz, with a chemical formula of SiO₂. Its purple color is caused by trace amounts of iron and natural irradiation within the crystal lattice. Amethyst forms in geodes and cavities within volcanic rocks. Historically, major sources included Russia and Brazil. Today, large deposits are found in Brazil, Uruguay, Zambia, and Namibia. Amethyst is relatively abundant compared to many other gemstones, which contributes to its affordability and widespread use.
Gemological Properties
The physical and optical properties of these gemstones are fundamental to their identity, value, and use in jewelry. The following table summarizes key gemological data for the December and February birthstones, based on the provided sources.
| Gemstone | Chemical Composition | Hardness (Mohs Scale) | Color Range | Notable Properties |
|---|---|---|---|---|
| Turquoise | CuAl₆(PO₄)₄(OH)₈·4H₂O | 5–6 | Sky blue to greenish hues | Opaque, porous, sensitive to heat and chemicals. |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) | 6–7 | Rich violet-blue, pleochroic (shows different colors from different angles) | Sensitive to heat and sunlight; trichroic (shows blue, violet, and red/brown). |
| Blue Topaz | Al₂SiO₄(F,OH)₂ | 8 | Pale sky blue to deep Swiss blue | Typically treated; very durable for everyday wear. |
| Blue Zircon | ZrSiO₄ | 6.5–7.5 | Bright, clear blue | High brilliance and fire; often heat-treated. |
| Amethyst | SiO₂ | 7 | Light to deep purple | A variety of quartz; color can fade with prolonged exposure to intense light. |
Hardness and Durability: Hardness, measured on the Mohs scale, is a critical factor in determining a gemstone's suitability for jewelry, especially for pieces worn daily. Blue topaz, with a hardness of 8, is the most durable of the December birthstones, making it highly resistant to scratching. Amethyst and blue zircon, with hardnesses of 7 and 6.5–7.5 respectively, are also quite durable. Tanzanite (6–7) and, most notably, turquoise (5–6) are significantly softer. Turquoise's low hardness and porous nature make it susceptible to scratches, dyes, and damage from chemicals, heat, and water.
Color and Clarity: Color is the most important factor for the value of these gemstones. For the December stones, the blue hue is paramount, though the specific shade varies dramatically. Turquoise is prized for its unique, often mottled blue-green color. Tanzanite is valued for its intense, saturated violet-blue and its pleochroism (displaying different colors when viewed from different crystal directions). Blue topaz and blue zircon are appreciated for their clear, brilliant blue. Amethyst's value is determined by the depth and saturation of its purple color, with deep "Siberian" purple being the most prized. Clarity is also important; for example, high-quality turquoise is often cut to show a uniform color, while tanzanite and zircon are expected to be eye-clean.
Treatments and Enhancements: Many of these gemstones undergo treatments to enhance their color or stability. Blue topaz is almost always irradiated and heat-treated to achieve its blue color. Blue zircon is frequently heat-treated to remove brownish tones and produce a vibrant blue. Tanzanite is routinely heat-treated to remove brownish components and enhance its blue color; this treatment is stable and widely accepted in the trade. Turquoise is often stabilized with resins or waxes to improve its durability and color, and dyed to enhance its hue. Amethyst is generally not treated, though it can be artificially irradiated to darken its color, and its natural color can fade with prolonged exposure to sunlight.
Symbolism and Metaphysical Beliefs
Gemstones have been imbued with symbolic meaning and metaphysical properties for millennia, a tradition that continues strongly with birthstones.
Turquoise is one of the oldest known gemstones in human history, with evidence of its use dating back to ancient Egypt, China, and Mesoamerican cultures. In these civilizations, turquoise was revered not only for its beauty but for its spiritual and protective properties. It was believed to bring good fortune, ward off evil, and serve as a bridge between the physical and spiritual worlds. In modern crystal healing, turquoise is believed to help with emotional healing, reduce anxiety, and enhance spiritual awareness. Its symbolism is deeply tied to protection, wisdom, and tranquility.
Tanzanite, as a relatively new gemstone, has developed modern symbolic meanings. It is often associated with transformation, new beginnings, and a higher consciousness. Its unique discovery in a single location and its vibrant, shifting colors lend themselves to metaphors of spiritual awakening and the discovery of one's unique path. Some sources also link it to communication and intuition.
Blue Topaz is often associated with calm, clarity, and communication. Its clear blue color evokes the sky and sea, symbolizing peace and emotional balance. In metaphysical beliefs, it is thought to aid in expressing one's thoughts and feelings clearly and to promote a sense of serenity.
Blue Zircon is traditionally associated with wisdom, clarity, and prosperity. Its high brilliance and fire are said to attract positive energy and good fortune. Some beliefs hold that it can help with sleep and provide protection during travel.
Amethyst has a long history of symbolism, particularly in connection with royalty and spirituality. In ancient Greece, it was believed to prevent intoxication and was associated with clarity of mind and temperance. Throughout history, it has been a stone of spirituality, contentment, and peace. Metaphysically, amethyst is considered a powerful protective stone, associated with calming the mind, enhancing intuition, and promoting spiritual growth.
Care and Cleaning
Proper care is essential for preserving the beauty and longevity of these birthstones, as their physical properties dictate specific maintenance requirements.
Turquoise requires the most careful handling due to its softness and porosity. It should be kept away from harsh detergents, perfumes, cosmetics, and excessive water, which can cause it to discolor or become damaged. To clean turquoise, use a soft cloth and mild soap with warm water. Avoid ultrasonic cleaners and steamers, as they can cause the stone to dry out, lose its color, or crack. Turquoise jewelry should be stored in a cool, dry place, separately from other gemstones to prevent scratches.
Tanzanite has a hardness of 6–7 and is sensitive to heat and sunlight, which can cause it to fade. It should be protected from prolonged exposure to direct sunlight. Cleaning should be done with a soft cloth and mild soap with warm water. Like turquoise, it should not be subjected to ultrasonic cleaners or steamers. Due to its cleavage (a tendency to split along flat planes), tanzanite should be handled with care to avoid sharp blows.
Blue Topaz and Blue Zircon are both relatively durable. Blue topaz, with a hardness of 8, is very resistant to scratching. Blue zircon, with a hardness of 6.5–7.5, is also quite durable but can be brittle due to its crystal structure. Both can be cleaned with warm water, mild soap, and a soft brush. They are generally safe for ultrasonic cleaners, but caution is advised for zircon due to its brittleness. They should be protected from sharp blows.
Amethyst has a hardness of 7 and is fairly durable. It can be cleaned with warm soapy water and a soft brush. It is generally safe for ultrasonic cleaners. However, prolonged exposure to intense sunlight or heat can cause its color to fade, so it is advisable to store amethyst jewelry away from direct light.
Conclusion
The birthstones of December and February present a compelling study in the evolution of gemstone traditions. December offers a diverse "azure palette" of blue stones—turquoise, tanzanite, blue topaz, and blue zircon—each with its own unique geological origin, historical significance, and gemological profile. This multiplicity reflects both the aesthetic appeal of blue gemstones and the modern trend of providing consumers with a range of options. In contrast, February's amethyst stands as a testament to timeless appeal, its rich purple hue and symbolic depth securing its place as a singular, enduring birthstone for over a century.
From the ancient protective talismans of turquoise to the modern, rare discovery of tanzanite, these stones bridge millennia of human culture. Their value is not merely monetary; it is found in their hardness and brilliance, their colors and inclusions, and the stories and beliefs they carry. For the gemstone enthusiast, jewelry buyer, or student of gemology, understanding the properties and histories behind these birthstones enriches the experience of owning and wearing them. Whether chosen for their beauty, durability, or symbolic meaning, the birthstones of December and February continue to captivate and inspire, connecting us to the deep, natural beauty of the Earth and the long history of human adornment.