GRADING REPORT OVTA174
- Identification: Natural Unheated & Untreated Tanzanite
- Carat: 1.74
- Shape: Oval
- Measures: 7.52x6.35x4.95 (millimeter)
- Color Grade: Good
- Tone: M50
- Color Zoning: Shifting and gradual
- Clarity: Free of Inclusions
- Cutting Grade: Good
o Brilliancy: 66%
o Depth: 78%
- Origin: Tanzania
- Treatment: None
Certificate No: IGI 329861885
Overall Grade: Good
Comment: Petrol-colored tanzanite in daylight, with more purple and violet in tungsten and mixed light. These type of zoisites are only lately brought to be classified by gem labs and I need to study their obvious color-change effects (see 'more images' under torch light), separated from their spectacular trichroism (the optical effect of three different colors in one gem). This 1.73 is mild in all color sections, far less vivid than in the IGI image. No inclusions, no treatments, no window, but an ancient hand-cut which becomes obvious under the lens (or on 36fold images). If precision cut is important for you, a re-cut can be arranged and there is potential to retain above one carat. BTW, when we use the description 'petrol-color', we mean the color effect of petrol on the surface of water (ignore environmental concerns for the moment), the fluidly moving mix of green, blue and purple. Always better than on images, I don't know why, especially in normal office light the gem turns surprisingly sparkly and petrol-type colorful. If you want a surprise-gem to brighten your cubicle days (are those terrible things still in use?) this may be a value snatch.
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