Tanzanite - The brilliance of a unique blue

Discovered at the foot of Kilimanjaro in 1967, tanzanite captivates with its intense color and unique blue-violet hues. A rare and precious stone, it embodies elegance and exoticism. It is one of the birthstones for December. Let us guide you in understanding, choosing, and showcasing this exceptional gem.

General information

Chemical formula: Hydroxylated calcium and aluminum silicate

  • Refractive index : 1.69 to 1.70
  • Optical character : positive biaxial
  • Density: 3.15 to 3.88
  • Hardness : 6.5 on the Mohs scale
  • Crystal system: orthorhombic
  • Color : blue to purple
  • Luster : vitreous
  • Strong pleochroism : blue to purple
  • Source: the only known source of tanzanite today is Tanzania
  • Treatment: heating at 300 to 400° to enhance the blue-purple color
  • Stones that resemble tanzanite: blue spinel, sapphire, blue glass, iolite, synthetic corundum

How to choose a Tanzanite?

  • Color

    A high-quality tanzanite features an intense blue with purple hues, sometimes slightly burgundy. The saturation should be high and even, with no visible zoning.

  • Purity

    The most prized stones are clean to the naked eye, without distracting inclusions, especially on the surface. Also watch out for internal fractures, which are more common in larger stones.

  • Size Style

    Cut plays an essential role. It must feature the right proportions and allow for excellent light dispersion. Cushion, brilliant, oval, or trillion cuts are particularly well suited to this gemstone.

  • Weight

    Small stones (0.5 to 1 ct) of decent quality: between €100 and €300/ct

    Gem quality (1 to 3 ct, vivid color, well-cut): €300 to €700/ct

    Exceptional tanzanites (>5 ct, top color): up to €1000/ct and more
View our tanzanites