December's birthstones are tanzanite — a violet-blue gemstone found only in Tanzania — and blue zircon, one of the oldest minerals on earth with exceptional brilliance.
Gemstone
Tanzanite & Blue Zircon
Colour
Tanzanite: violet-blue | Blue Zircon: vivid sky blue
Hardness
Tanzanite: 6.5–7 Mohs | Blue Zircon: 7.5 Mohs
Symbolism
Transformation, clarity, and new beginnings
Tanzanite was discovered in 1967 in the foothills of Mount Kilimanjaro and has been found nowhere else on earth. This single-source origin makes it approximately 1,000 times rarer than diamond. Geologists estimate the supply could be exhausted within the next 20-30 years, adding to its collectibility.
Blue zircon should not be confused with cubic zirconia (a synthetic diamond simulant). Natural zircon is one of the oldest minerals on earth — some zircon crystals are over 4.4 billion years old. Its high refractive index gives it exceptional brilliance that can rival diamond.
Tanzanite's remarkable trichroism means it displays three different colours when viewed from different angles: blue, violet, and burgundy. The most valued stones appear a rich, saturated violet-blue in daylight — a colour unique in the gemstone world.
Tanzanite's violet-blue colour looks magnificent in white gold or platinum. Due to its moderate hardness (6.5-7 Mohs), tanzanite is best suited for earrings, pendants, and occasion rings with protective settings. Blue zircon is more durable and suitable for everyday rings.
December has two main birthstones: tanzanite and blue zircon. Tanzanite is a violet-blue stone found only in Tanzania, making it exceptionally rare. Blue zircon is a natural gemstone with brilliant fire and one of the oldest minerals on earth.
Tanzanite's single-source origin and potentially finite supply have made it increasingly collectible. While gemstones should be purchased for enjoyment rather than investment, fine-quality tanzanites have appreciated significantly in value over the past two decades.
No — they are completely different materials. Blue zircon is a natural gemstone (zirconium silicate) that has been forming in the earth for billions of years. Cubic zirconia is a synthetic material (zirconium dioxide) manufactured as a diamond substitute.