Tanzanite
- Hardness
- 6.5 to 7
- Refractive index
- 1.692 to 1.706 with birefringence of 0.013 approximatively
- Specific gravity
- 3.35
Nomenclature
Indicative weight
– carats
| Dimensions (mm) | Weight (ct) |
|---|
All shapes side by side
| Dimensions (mm) | Weight (ct) |
|---|---|
| 2.00 | 0.04 |
| 2.50 | 0.07 |
| 3.00 | 0.11 |
| 3.50 | 0.13 |
| 4.00 | 0.23 |
| 4.50 | 0.28 |
| 5.00 | 0.41 |
| 5.50 | 0.52 |
| 6.00 | 0.67 |
| 7.00 | 1.29 |
| Dimensions (mm) | Weight (ct) |
|---|---|
| 4 × 3 | 0.18 |
| 5 × 3 | 0.38 |
| 6 × 4 | 0.65 |
| 7 × 5 | 0.96 |
| 8 × 6 | 1.45 |
| 9 × 7 | 2.03 |
| 10 × 8 | 2.85 |
| 11 × 9 | 3.55 |
| Dimensions (mm) | Weight (ct) |
|---|---|
| 4 × 2 | 0.07 |
| 5 × 2.5 | 0.14 |
| 6 × 3 | 0.21 |
| 8 × 4 | 0.47 |
| 10 × 5 | 0.91 |
| 12 × 6 | 1.37 |
| Dimensions (mm) | Weight (ct) |
|---|---|
| 3.0 | 0.07 |
| 4.0 | 0.17 |
| 4.5 | 0.30 |
| 5.0 | 0.36 |
| 5.5 | 0.51 |
| 6.0 | 0.6 |
| 7.0 | 0.97 |
| 8.0 | 1.38 |
| Dimensions (mm) | Weight (ct) |
|---|---|
| 4 × 3 | 0.17 |
| 5 × 3 | 0.22 |
| 6 × 4 | 0.28 |
| 7 × 5 | 0.92 |
| 8 × 6 | 1.36 |
| 9 × 7 | 1.97 |
| 10 × 8 | 3.01 |
| 11 × 9 | 4.11 |
| 12 × 10 | 5.08 |
| Dimensions (mm) | Weight (ct) |
|---|---|
| 5 × 3 | 0.16 |
| 6 × 4 | 0.31 |
| 7 × 5 | 0.55 |
| 8 × 5 | 0.69 |
| 9 × 6 | 1.11 |
| 10 × 7 | 1.51 |
| 12 × 8 | 2.42 |
| Dimensions (mm) | Weight (ct) |
|---|---|
| 2.0 | 0.04 |
| 2.5 | 0.06 |
| 3.0 | 0.13 |
| 3.5 | 0.18 |
| 4.0 | 0.27 |
| 4.5 | 0.42 |
| 5.0 | 0.49 |
| 5.5 | 0.59 |
| 6.0 | 0.88 |
| 7.0 | 1.43 |
Sources
This blue zoisite can only be found in Tanzania.
Common treatments
A significant proportion of rough tanzanites have brownish yellow tints that can be removed by carefully heating the tanzanites up to 500°C.
Tanzanites should have a very high clarity as a heat-treatment could open a fracture or enlarge an inclusion in the gemstone and break it.
Care and cleaning
Handle tanzanite with care, avoid impacts.
Working with tanzanite requires a lot of care because its cleavage can be tricky.
– Pay more attention when using ultrasound and steam jets
– Thermal shocks should be avoided
– keep the tanzanite away from acidic substances
Clean with warm soapy water and dry with a soft cloth.