December is unique among the months, boasting not one, but four recognized birthstones: turquoise, blue zircon, blue topaz, and tanzanite. All four gemstones share a common thread – a beautiful range of blue hues – but each possesses distinct geological origins, historical significance, and gemological properties. This article will delve into the characteristics of each of these December birthstones, exploring their history, sources, properties, and symbolism, as understood through available gemological and historical data.
History and Lore
The history of December’s birthstones is rich and varied. Turquoise, perhaps the most anciently recognized of the four, has been cherished for millennia. Ancient Egyptians adorned themselves with turquoise, and Chinese artisans were carving it over 3,000 years ago. The stone was believed to guarantee health and good fortune, and from the 13th century onward, it was thought to offer protection from falls and warn of impending disaster. Hindu mystics associated turquoise with wealth gained after observing the new moon.
Blue zircon, while also possessing a long history, has sometimes been confused with its synthetic counterpart, cubic zirconia. Historically, colorless zircon was used as a diamond substitute due to its brilliance. The other two December birthstones, blue topaz and tanzanite, have more recent claims to fame. Tanzanite, discovered relatively recently, quickly gained popularity for its striking color, while blue topaz became a favored alternative to zircon due to its availability in larger sizes and more affordable price point.
Geological Formation and Sources
Each of these gemstones originates through distinct geological processes and is sourced from specific regions around the globe. Turquoise forms in relatively shallow deposits, often as a secondary mineral in arid regions. Notable sources include Iran (producing highly prized “Persian-Grade” turquoise with a robin’s egg blue color and no visible matrix), Egypt (yielding greener, more translucent turquoise), and the United States, particularly Arizona, with mines like Sleeping Beauty and Kingman producing sky blue to deep blue stones with varying matrix patterns. Virginia is also home to a unique source, Lynch Station, which produces transparent turquoise. Mexico’s Sonoran Gold turquoise is known for its baby blue and lime green hues with yellow web matrix.
Blue zircon is sourced from Sri Lanka, Vietnam, Cambodia, and Myanmar. The gemstone’s formation involves complex geological processes within igneous and metamorphic rocks.
Blue topaz is a variety of topaz that is often created through heat treatment of naturally occurring colorless or pale topaz. Natural sources of topaz exist globally, but the blue variety is frequently produced through irradiation and heat treatment.
Tanzanite, discovered in the Merelani Hills of Tanzania, is found in a very limited geographical area, making it a relatively rare gemstone. It forms within metamorphic rocks and is exclusively mined in Tanzania.
Gemological Properties
The four December birthstones exhibit a range of gemological properties. Turquoise is a semi-translucent to opaque gem, its color stemming from copper (blue), chromium or vanadium (green), or iron (yellow) impurities. Its quality is assessed based on color, matrix, and texture, with dense textures exhibiting better polish luster.
Zircon displays a wide spectrum of colors, with blue being the most popular, often achieved through heat treatment. It possesses a very high refractive index, contributing to its brilliance. Zircon also contains trace amounts of uranium and thorium, making it useful in radiometric dating, with some specimens dating back 4.4 billion years. Radioactive elements within zircon can cause changes to its structure over time, affecting its color and properties.
Blue topaz, chemically a silicate of aluminum and fluorine, is known for its affordability and availability in large sizes. Its color is typically achieved through irradiation and heat treatment.
Tanzanite, a calcium aluminum silicate, is known for its strong pleochroism, meaning it displays different colors when viewed from different angles. It typically ranges from purple to blue, with vibrant pure blue being the most valuable color.
The following table summarizes key properties:
| Gemstone | Chemical Composition | Color(s) | Hardness (Mohs) | Transparency |
|---|---|---|---|---|
| Turquoise | Copper Aluminum Phosphate Hydrate | Blue, Green, Yellowish-Green | 5-6 | Opaque |
| Blue Zircon | Zirconium Silicate | Blue (often heat-treated), Green, Red | 6.5-7.5 | Transparent to Opaque |
| Blue Topaz | Aluminum Fluorosilicate | Blue (often irradiated/heat-treated) | 8 | Transparent |
| Tanzanite | Calcium Aluminum Silicate | Blue, Violet-Blue, Purplish-Blue | 6-7 | Transparent |
Symbolism and Metaphysical Beliefs
Throughout history, each of these gemstones has been attributed with various symbolic meanings and metaphysical properties. Turquoise has long been associated with protection, good fortune, and health. It was believed to ward off negative energy and promote healing.
Zircon, in various colors, has been linked to prosperity and wisdom. Blue zircon, specifically, is often associated with calmness and clarity.
Blue topaz is believed to promote communication, honesty, and self-confidence. It is often associated with loyalty and affection.
Tanzanite is thought to stimulate intuition and spiritual awareness. It is also believed to promote transformation and positive energy.
Care and Cleaning
The care and cleaning of these December birthstones vary based on their hardness and other properties. Turquoise, being relatively soft, requires gentle handling and should be protected from scratches and harsh chemicals. Cleaning can be done with a soft cloth and mild soapy water.
Zircon, with its good hardness, can be cleaned with warm soapy water and a soft brush. However, it should be protected from sudden temperature changes.
Blue topaz, being a hard and durable gemstone, can withstand regular wear and cleaning with warm soapy water and a soft brush. Ultrasonic cleaners can be used with caution.
Tanzanite, while relatively durable, is susceptible to damage from heat and chemicals. It should be cleaned with warm soapy water and a soft cloth, and ultrasonic cleaners should be avoided.
Conclusion
December’s birthstones – turquoise, blue zircon, blue topaz, and tanzanite – represent a diverse and captivating collection of gemstones. Each stone boasts a unique history, geological origin, and set of gemological properties. From the ancient lore surrounding turquoise to the modern appeal of tanzanite, these gemstones continue to fascinate and inspire. Whether chosen for their beauty, symbolism, or personal significance, these December birthstones offer a vibrant spectrum of color and meaning.