A December Dilemma: Turquoise, Tanzanite, or Zircon?

For those born in the final month of the year, December offers a rare gemmological privilege. Instead of a single birthstone, this month presents three remarkable choices: earthy turquoise, rare tanzanite, and brilliant zircon. More than simple alternatives, each gemstone carries a complete narrative shaped by geology, cultural history, and beauty.

Turquoise: The Ancient Sky Stone

Turquoise is a hydrated phosphate of copper and aluminium. Its vivid blue colour is created by copper ions, while traces of iron can produce gentle green tones. This opaque mineral forms in the dry, oxidised zones above copper deposits, often appearing as nodules or fine veinlets. With a Mohs hardness of five to six, turquoise is relatively soft and porous, so it requires mindful care, especially as it can be affected by chemicals, sunlight, and heat.

Turquoise is among the oldest gemstones ever used by humans. Archaeological finds, including adornments on Egyptian mummies, trace its history back more than six thousand years. From ancient Persia to Native American cultures, it has long been valued as a sacred material believed to offer protection and spiritual strength. Its opaque surface, sometimes marked by natural matrix patterns, evokes desert landscapes and endless skies, symbolising serenity, wisdom, and a deep connection to ancestral heritage.

Lot 772

Circular-shape turquoise cabochons, 65.18ct

Estimate £50 -£80

Tanzanite: The Modern Marvel

Discovered only in 1967, tanzanite is a relatively newcomer in the world of gemstones. It is the blue to violet-blue variety of the mineral zoisite. While it often forms naturally in brownish tones, its celebrated shades of sapphire blue and violet are created through controlled heat treatment between five hundred and six hundred degrees Celsius, a stable and widely accepted process. Tanzanite is strongly pleochroic, showing different colours such as blue, violet, and burgundy depending on the viewing angle. With a Mohs hardness of six to seven, it benefits from protective settings when worn in jewellery.

Tanzanite’s appeal lies in its remarkable rarity. It comes from a single small region near Mount Kilimanjaro in Tanzania, covering an area of only around 20 square kilometres. This geographical exclusivity, combined with its vibrant colour, propelled it to global fame. Tiffany and Co. recognised its potential immediately and named it tanzanite to highlight its unique origin. It represents sophistication, modernity, and a sense of exclusivity.

Lot 504

Pear-shape tanzanite, 3.88ct

Estimate £250 - £350

Zircon: The Timekeeper

Zircon is a magnificent gemstone, celebrated for its exceptional brilliance and fire, the ability to scatter light into coloured flashes that can rival diamonds. Beyond its beauty, zircon is a geologist's treasure. Its crystal structure traps uranium and thorium atoms while excluding lead, creating a precise radiometric clock. The uranium-lead decay in these crystals allows scientists to date them with remarkable accuracy. Zircons around 4.4 billion years old provide the earliest evidence of a solid crust on Earth.

For the wearer, zircon is both dazzling and historically significant, connecting personal adornment to the deepest timelines of our planet.

Lot 705

Oval-shape zircon, 8.18ct

Estimate £40 - £60

Choosing Your December Birthstone

Whether you are drawn to the ancient sky blue of turquoise, the exclusive violet blue of tanzanite, or the brilliant fire of zircon, those born in December can choose a gemstone that reflects not only personal style but also the richness of human heritage and time itself.