The Rich Legacy and Diversity of December’s Birthstones: A Triad of Blue Gemstones

December is a month of transition and celebration, marked by the winter solstice, the culmination of the holiday season, and the anticipation of a new year. Among its many traditions, the month is uniquely distinguished by having three officially recognized birthstones: tanzanite, turquoise, and zircon (particularly blue zircon). This multiplicity is a rare and fascinating phenomenon in the world of birthstones, which are typically associated with a single gemstone per month. The inclusion of three stones for December reflects a dynamic evolution in gemological and cultural traditions, shaped by centuries of historical use, commercial development, and geological discovery.

This article explores the historical, cultural, and gemological significance of December’s three birthstones, examining why the month is associated with multiple gemstones, what distinguishes each of them, and how they have come to represent the spirit of December. Drawing from authoritative sources and historical records, we will uncover the stories behind each gemstone and their roles in both ancient and modern traditions.

The Historical Evolution of December’s Birthstones

The tradition of associating gemstones with months of the year has ancient roots, with early references found in biblical texts and other ancient cultural records. One of the earliest known lists of gemstones linked to months comes from the Biblical Book of Exodus, where the High Priest’s breastplate is described as containing 12 stones, each representing one of the 12 tribes of Israel. However, these early lists varied significantly by region and culture, and it wasn’t until the 20th century that a standardized list of birthstones was established.

The Standardization of Birthstones in the 20th Century

The 1912 list, standardized by the National Association of Jewelers (now known as the Jewelers of America), was the first widely accepted modern birthstone list in the United States. This list originally assigned turquoise as the primary December birthstone and lapis lazuli as an alternative. This list remained largely unchanged for decades, with turquoise being the dominant December stone in jewelry and cultural references.

However, in 1952, the Jewelry Industry Council of America updated the list to include zircon as a primary December birthstone. This addition was driven by zircon’s increasing popularity and its physical properties, which made it a more durable and brilliant option compared to lapis lazuli.

The most recent addition to the December birthstone list occurred in 2002, when tanzanite was officially recognized as a December birthstone by the American Gem Trade Association (AGTA). Tanzanite, a relatively new gemstone discovered in 1967 in Tanzania, was chosen for its striking blue and violet hues, which aligned with the December color palette and its rarity, which made it a compelling addition to the list.

The Rationale Behind Three Birthstones

The inclusion of three birthstones for December is not arbitrary. Rather, it reflects a combination of historical continuity, gemological diversity, and cultural symbolism. Each of the three gemstones—tanzanite, turquoise, and zircon—has a distinct history and set of properties that contribute to the richness of December’s birthstone tradition.

Turquoise, with its deep blue-green hues, has been used in jewelry and adornment for thousands of years, particularly by ancient civilizations in the Middle East, Egypt, and Native American cultures. Its connection to December likely dates back to the 1300s, when it was associated with health, wealth, and happiness. The cool blue tone of turquoise also mirrors the color of the winter sky, reinforcing its symbolic association with the month.

Zircon, particularly the blue variety, emerged as a popular alternative in the 20th century due to its brilliance, durability, and affordability. Blue zircon’s vibrant color and refractive properties made it a natural fit for December, and its addition to the official list in 1952 was a response to the changing preferences of consumers and jewelers.

Tanzanite, the newest addition to the December birthstone list, was introduced in 2002 to reflect the modern era of gemstone discovery and marketing. Discovered in a single location in Tanzania, tanzanite is one of the rarest gemstones in the world and is known for its trichroism—the ability to display three different colors (blue, purple, and burgundy) depending on the viewing angle. Its inclusion in the December list not only honored the rarity of the gem but also expanded the diversity of December’s birthstone offerings.

Together, these three gemstones provide a rich tapestry of color, history, and symbolism, making December’s birthstone tradition one of the most unique and multifaceted in the world.

The Gemological Properties of December’s Birthstones

Each of the three December birthstones—tanzanite, turquoise, and zircon—possesses distinct chemical compositions, physical properties, and optical characteristics that define their appearance and value. Understanding these properties helps to appreciate the scientific basis for their selection and the ways in which they differ from one another.

Tanzanite

• Chemical Composition: Tanzanite is a variety of the mineral zoisite, with the chemical formula Ca₂Al₃(SiO₄)(OH)₃(O₂). Its striking blue and violet colors are caused by the presence of violet and blue trace elements, particularly vanadium and chromium, which are activated by heat treatment.
• Color: Tanzanite is known for its deep, saturated blue and violet hues, with some stones displaying a trichroic effect—the ability to show three different colors (blue, purple, and burgundy) depending on the viewing angle.
• Hardness: On the Mohs scale of mineral hardness, tanzanite has a hardness of 6 to 6.5, making it relatively soft compared to other gemstones. It is also cleavage-prone, meaning it can be easily fractured along certain planes.
• Refractive Index: Tanzanite has a refractive index of 1.694 to 1.702, contributing to its vibrant sparkle and depth of color.
• Luster: Tanzanite has a vitreous (glassy) luster, which enhances its brilliance and makes it highly desirable in jewelry.

Turquoise

• Chemical Composition: Turquoise is a phosphate mineral with the chemical formula CuAl₆(PO₄)₄(OH)₈·4H₂O. It is composed of copper, aluminum, phosphorus, and water, which contribute to its bluish-green color.
• Color: The color of turquoise can range from pale blue to deep green, depending on the proportions of copper and aluminum within the stone. The presence of iron can also influence the color, producing greenish or brownish tones.
• Hardness: Turquoise has a Mohs hardness of 5 to 6, making it relatively soft and prone to scratching and damage.
• Refractive Index: Turquoise has a low refractive index of 1.61 to 1.65, which gives it a subtle, waxy luster rather than a brilliant sparkle.
• Luster: Turquoise has a waxy to greasy luster, which contributes to its natural, earthy appearance.

Zircon

• Chemical Composition: Zircon is a zirconium silicate with the chemical formula ZrSiO₄. It is found in blue, yellow, red, and colorless forms, with blue zircon being the most commonly associated with December.
• Color: Blue zircon is known for its brilliant, deep blue color, which is enhanced through heat treatment. Natural zircon can occur in a wide range of colors, but the blue variety is the most popular in jewelry.
• Hardness: Zircon has a Mohs hardness of 6 to 7.5, depending on the crystal structure. This makes it more durable than turquoise but still softer than many other gemstones.
• Refractive Index: Zircon has a high refractive index of 1.92 to 2.00, which gives it a sparkling, glassy appearance and makes it a popular alternative to diamonds.
• Luster: Zircon has a vitreous (glassy) luster, which enhances its brilliance and fire.

Cultural and Metaphysical Significance of December’s Birthstones

Beyond their gemological properties, December’s birthstones have long been associated with cultural symbolism, spiritual meanings, and metaphysical beliefs. These associations have been passed down through generations and continue to influence the way these gemstones are used in jewelry, therapy, and spiritual practices.

Tanzanite

Tanzanite is often associated with spiritual growth, intuition, and emotional healing. It is believed to enhance psychic abilities and promote a deep sense of inner peace and clarity. In some traditions, tanzanite is used in meditation and energy healing to help balance the mind, body, and spirit.

• Spiritual Meaning: Tanzanite is said to open the third eye chakra, enhancing intuition and spiritual awareness.
• Healing Properties: It is believed to promote emotional balance, reduce anxiety, and foster compassion and empathy.
• Modern Use: Tanzanite is also a traditional gift for the 24th wedding anniversary, symbolizing deep emotional connection and enduring love.

Turquoise

Turquoise has been one of the most revered and widely used gemstones in history, with a rich cultural significance across many civilizations. It has been used as a protective stone, a symbol of wisdom, and a representation of divine favor.

• Cultural Significance: Turquoise has been used in ancient Egypt, Persia, China, and the Americas for thousands of years. In Native American cultures, it is often associated with protection, healing, and spiritual guidance.
• Metaphysical Properties: Turquoise is believed to stimulate wisdom, trust, and understanding, and to strengthen the immune system. It is also thought to aid in the absorption of nutrients and regulate fluids in the body.
• Modern Use: Turquoise is frequently used in jewelry and decorative objects, particularly in Native American and Middle Eastern styles. It is also used in healing practices to promote calmness and emotional stability.

Zircon

Zircon, particularly the blue variety, is associated with clarity, honor, and emotional balance. It is believed to bring prosperity, protect against nightmares, and foster love and harmony.

• Historical Use: Zircon has been used in ancient jewelry and religious artifacts, particularly in Babylonian and Indian cultures. It was often believed to bring good fortune and divine protection.
• Metaphysical Properties: Zircon is believed to relieve pain and inflammation, promote self-esteem and clarity, and protect against negative energies.
• Modern Use: Blue zircon is a popular alternative to diamonds due to its sparkling appearance and affordability. It is also used in spiritual practices to enhance emotional well-being and spiritual insight.

The Symbolism of Blue in December’s Birthstones

One of the most unifying elements of December’s three birthstones is their dominant blue color palette, which has long been associated with wisdom, protection, and spiritual growth. The cool, calming tones of tanzanite, turquoise, and zircon reflect the winter season, the transition into a new year, and the quiet introspection that often accompanies the holiday season.

In many cultures, blue is a symbol of the sky and the sea, representing infinity, depth, and the unknown. In Eastern traditions, blue is associated with fertility, health, and protection, while in Western traditions, it is often linked to trust, loyalty, and calmness.

The triple blue gemstones of December—tanzanite, turquoise, and zircon—each embody different shades and meanings of blue, contributing to the rich symbolism of the month. Whether it’s the deep, velvety blue of tanzanite, the warm, earthy blue-green of turquoise, or the brilliant, glassy blue of zircon, each stone represents a different aspect of December’s spirit—from celebration and joy to reflection and renewal.

Care and Maintenance of December Birthstones

Given the variability in hardness and durability among December’s three birthstones, it is important to understand the best practices for cleaning and maintaining these gemstones to preserve their beauty and longevity.

Tanzanite

• Hardness: 6–6.5 on the Mohs scale.
• Care Tips:
  • Avoid exposure to heat or direct sunlight, as tanzanite can fade if exposed to high temperatures or prolonged UV light.
  • Clean gently with warm, soapy water and a soft cloth. Avoid using harsh chemicals or ultrasonic cleaners, which can damage the stone.
  • Store tanzanite separately from harder gemstones to prevent scratching.
  • Avoid wearing tanzanite during physical activities, as it is prone to chipping and cleavage.

Turquoise

• Hardness: 5–6 on the Mohs scale.
• Care Tips:
  • Avoid exposure to water, as turquoise is porous and can absorb liquids, causing discoloration or damage.
  • Clean with a soft cloth and mild soap, avoiding harsh chemicals or abrasive cleaners.
  • Store turquoise in a dry, cool place to prevent drying out or cracking.
  • Avoid wearing turquoise during physical activities, as it is soft and easily scratched.

Zircon

• Hardness: 6–7.5 on the Mohs scale.
• Care Tips:
  • Zircon is relatively durable, but it can be damaged by sudden temperature changes or exposure to heat.
  • Clean with warm, soapy water and a soft cloth. Avoid using ultrasonic cleaners, as they can damage the internal structure of the stone.
  • Store zircon in a soft cloth or padded jewelry box to prevent scratching from harder gemstones.
  • Avoid exposing zircon to acidic substances, which can dull its luster.

Conclusion

December is a month of transition, celebration, and reflection, and its three birthstones—tanzanite, turquoise, and zircon—reflect this duality with their rich history, diverse properties, and deep symbolism. From the ancient use of turquoise in ceremonial and protective jewelry to the modern discovery and marketing of tanzanite, December’s birthstones tell a story of cultural evolution, gemological science, and spiritual meaning.

The inclusion of three birthstones for December is not merely a matter of tradition but a reflection of the dynamic nature of gemstone appreciation over time. Each of these gemstones offers a unique expression of the month’s spirit, from the deep, mystical blue of tanzanite to the warm, earthy tones of turquoise and the sparkling brilliance of zircon. Together, they form a rich and diverse tapestry of color, history, and meaning that continues to captivate gemstone enthusiasts, jewelers, and historians alike.

Sources

1. Why Does December Have Four Birthstones? Tanzanite, Turquoise, Zircon, Blue Topaz
2. December Birthstones: A Trio of Jewels for the Year’s End
3. December Birthstones: A Triad of Beauty, History, and Meaning
4. Why Does December Have 3 Birthstones?
5. December's Birthstone: A Guide to Tanzanite, Turquoise, and Zircon
6. December Birthstone – Tanzanite, Turquoise & Zircon