December is unique among the calendar months, boasting not one, but four recognized birthstones: blue topaz, blue zircon, tanzanite, and turquoise. Each of these gemstones presents a distinct shade of blue, mirroring the cool tones of the winter season, and carries its own rich history and symbolism. While turquoise holds the distinction as the most traditional December birthstone, tanzanite represents a more recent discovery, unearthed in Tanzania in 1967. These stones are associated with qualities like wisdom, protection, and new beginnings, offering December-born individuals a diverse selection to express their individuality.
History and Lore
The history of December’s birthstones spans millennia. Turquoise, one of the oldest known gemstones, has been prized for thousands of years by cultures across the globe. Evidence suggests its use dates back to 3000 BCE, with ancient civilizations in Egypt and Persia valuing it for its sky-blue color and perceived protective powers. Turquoise symbolizes peace, health, and good fortune, a legacy carried through centuries of adornment and ritual.
Zircon, while often overshadowed, also possesses a long history. Tanzanite, however, is a comparatively recent addition to the world of gemstones. Discovered in 1967 in the Merelani Hills of Tanzania, it was initially misidentified as blue zoisite before being officially named tanzanite in honor of its country of origin. Its rapid rise in popularity is a testament to its exceptional beauty and rarity. Blue topaz, though a long-appreciated gem, gained prominence as a December birthstone more recently, offering a bright and accessible alternative.
Geological Formation and Sources
The origins of these December birthstones are as varied as their appearances. Turquoise forms through a unique geological process involving rainwater or melted snow percolating through copper ore deposits. This water interacts with copper sulfides, creating an acidic solution that reacts with aluminum and potassium in surrounding rocks, ultimately precipitating turquoise into cavities within weathered volcanic and sedimentary rock, typically found in arid regions.
Zircon forms in igneous rocks and metamorphic rocks, often as a byproduct of magma crystallization. Blue zircon’s color is often achieved through heat treatment of naturally occurring brown or reddish zircon. Tanzanite, uniquely, is found exclusively in the Merelani Hills of northern Tanzania, making it one of the rarest gemstones on Earth. It forms within metamorphic rocks, a result of intense heat and pressure. Blue topaz is typically created through irradiation of colorless topaz, which itself forms in granite pegmatites and volcanic rocks.
Gemological Properties
Each of the December birthstones possesses distinct gemological properties. Turquoise, a copper aluminum phosphate, registers a Mohs hardness of 5 to 6, making it relatively soft and susceptible to scratching. It is opaque and porous, and its color can be affected by oils, pigments, and even changes in water content.
Zircon boasts a higher hardness, ranging from 6.5 to 7.5 on the Mohs scale, and exhibits strong double refraction. It occurs in a variety of colors, including blue, golden, red, and clear. Blue zircon’s color is often enhanced through heat treatment. Tanzanite, a calcium aluminum silicate, has a hardness of 6 to 7 on the Mohs scale. It is known for its trichroism – displaying different colors (blue, violet, and burgundy) when viewed from different angles – and its strong pleochroism, where different colors are visible depending on the viewing direction.
Blue topaz, an aluminum silicate fluoride hydroxide, has a hardness of 8 on the Mohs scale, making it a durable gemstone. Its color is typically achieved through irradiation, and it exhibits a vitreous luster.
Here's a comparative table of the gemstones' hardness:
| Gemstone | Mohs Hardness |
|---|---|
| Turquoise | 5-6 |
| Zircon | 6.5-7.5 |
| Tanzanite | 6-7 |
| Blue Topaz | 8 |
Symbolism and Metaphysical Beliefs
Throughout history, each of these gemstones has been imbued with symbolic meaning. Turquoise has long been associated with protection, healing, and good fortune, particularly in Native American cultures. It is believed to promote peace and tranquility. Zircon, historically, was thought to ward off evil spirits and promote restful sleep.
Tanzanite is believed to possess high-vibration healing energy, acting as a spiritual guide and fostering wisdom and consciousness. It is associated with transformation and intuition. The deep blue-violet color of tanzanite is often linked to inner strength and peace. Blue topaz symbolizes loyalty, intellect, and communication. It is thought to promote clarity of thought and emotional stability.
Care and Cleaning
Due to their varying hardness and properties, each December birthstone requires specific care. Turquoise, being relatively soft and porous, should be protected from scratches and harsh chemicals. Cleaning should be done gently with a soft cloth and mild soapy water. Avoid ultrasonic cleaners and steam cleaners.
Zircon, with its good hardness, can be cleaned with warm soapy water and a soft brush. However, avoid sudden temperature changes. Tanzanite, while durable, is susceptible to damage from heat and chemicals. It should be cleaned with warm soapy water and a soft cloth. Ultrasonic cleaners should be avoided. Blue topaz, being a relatively hard gemstone, can be cleaned with warm soapy water, a soft brush, and ultrasonic cleaners. However, avoid harsh chemicals.
The 24th Wedding Anniversary
Tanzanite holds a special significance beyond being a December birthstone; it is also the traditional gemstone gifted to celebrate a 24th wedding anniversary, symbolizing enduring love and commitment.