Peridot

Peridot

Hardness
6.5 to 7
Refractive index
1.654 to 1.690 with a birefringence of 0.036
Specific gravity
3.31 to 3.48

Nomenclature

Shape

Indicative weight

– carats

Dimensions (mm)Weight (ct)

A calibrated series, to scale

All shapes side by side
Round
Dimensions (mm)Weight (ct)
2.000.04
2.500.08
3.000.13
3.500.18
4.000.31
4.500.38
5.000.55
5.500.70
6.000.91
7.001.75
Oval
Dimensions (mm)Weight (ct)
4 × 30.16
5 × 30.25
6 × 40.51
7 × 50.88
8 × 61.30
9 × 71.97
10 × 82.76
11 × 93.86
12 × 104.81
14 × 105.77
Marquise
Dimensions (mm)Weight (ct)
4 × 20.10
5 × 2.50.19
6 × 30.29
8 × 40.64
10 × 51.23
12 × 61.85
15 × 73.54
16 × 84.22
18 × 96.31
20 × 109.17
Heart
Dimensions (mm)Weight (ct)
3.00.10
4.00.23
4.50.40
5.00.49
5.50.69
6.00.81
7.01.32
8.01.87
9.02.57
10.03.82
Octagon
Dimensions (mm)Weight (ct)
4 × 30.23
5 × 30.30
6 × 40.38
7 × 51.25
8 × 61.84
9 × 72.67
10 × 84.08
11 × 95.57
12 × 106.89
14 × 107.09
Pear
Dimensions (mm)Weight (ct)
5 × 30.21
6 × 40.43
7 × 50.74
8 × 50.94
9 × 61.50
10 × 72.04
12 × 83.28
14 × 94.61
15 × 106.01
16 × 128.86
Square
Dimensions (mm)Weight (ct)
2.00.05
2.50.09
3.00.18
3.50.24
4.00.36
4.50.56
5.00.66
5.50.80
6.01.19
7.01.94

Sources

Pakistan, China, Myanmar, and the United States

Common treatments

This stone is rarely treated. However, a heat treatment will brighten the darkest stones.

Cracks can be filled with oil, wax or colourless resin whereas fractures will be filled with epoxy resin.

Care and cleaning

Because of his medium hardness, a peridot will easily scratches and grinds off.

Impacts should be avoided.

It is better to avoid even slight contact with cosmetics, perfumes, hairspray or acidic substances.

Ultrasound and steam jets are not recommended either.

Gem cutters know that this stone is not easy to work on. There are often lots of tensions inside the crystal.