GRADING REPORT emS078
- Identification: Natural Unheated & Untreated Color Change Sapphire
- Carat: 0.78
- Shape: Emerald
- Measures: 3.80x5.75x3.42 (millimeter)
- Color Grade: Good
- Tone: M60
- Color Zoning: None
- Clarity: Free of Inclusions
- Cutting Grade: Very Good
o Brilliancy: 50%
o Depth: 90%
- Origin: Usambara, Tanzania
- Treatment: None
Certificate No: TGL19010253 (see more images)
Overall Grade: Good+ ('+' for the rare color effect)
Comment: Unique type of color-change sapphire. The mild colors move between green and purple in parallel lines. In the main image you can see the left part in mauve purple, while the right is green, with the colors separating along straight lines, an effect called 'Usambara'. This is theoretically not (but practically still) based on different lightwaves. It's a bit more too complicated to explain here. Please, see the link above. Obviously, neither color is flashy but mixed with grey. While the usual color-change in sapphire is blue-to-purple, Tanzania has produced this type green-purple color-change (also found in Tourmaline). It's hard to believe that all images come from the same gem, but so it is. Obviously, all CC-effects must be shown under torch-light to strengthen what the eye perceives in plain light. Nevertheless, such a gem needs study and patience. Gemological rarities are probably most interesting for the collector. Nevertheless, this sapphire is clean, well cut, untreated and shows no window, in case you like to wear a unique gem in jewelry.
Ask a question.
