Natural Tourmaline 27.88 Carats Usambara effect

Rarest of the Rare. The "Usambara effect" displayed by this enormous (nearly 28 carats!) Tourmaline is one of the rarest natural phenomena on the planet. It's a complex structural feature which in the case of this exceptional gem causes the jewel to flash from deep green to brilliant red. This is caused by unique features in the crystal formation which are not entirely understood. We managed to get our hands on this one, and it's worthy of a very special place in a special collection.
Gemstone Details

• Identification: Natural Tourmaline
• Carat: 27.88 Carats
• Shape: Oval
• Color: Brown Green
• Measurements: 21.85 x 16.62 mm