Emerald

Emerald

Hardness
7.5 to 8
Refractive index
1.577 to 1.583 with birefringence from 0.005 to 0.009
Specific gravity
2.67 to 2.84

Nomenclature

Shape

Indicative weight

– carats

Dimensions (mm)Weight (ct)

A calibrated series, to scale

All shapes side by side
Round
Dimensions (mm)Weight (ct)
2.000.03
2.500.06
3.000.10
3.500.16
4.000.24
4.500.31
5.000.45
5.500.60
6.000.77
7.001.10
Oval
Dimensions (mm)Weight (ct)
4 × 30.16
5 × 30.22
6 × 40.42
7 × 50.65
8 × 61.06
9 × 71.58
10 × 82.09
11 × 93.15
Marquise
Dimensions (mm)Weight (ct)
4 × 20.08
5 × 2.50.12
6 × 30.22
8 × 40.49
10 × 50.88
Heart
Dimensions (mm)Weight (ct)
3.00.13
4.00.31
4.50.33
5.00.43
5.50.56
6.00.92
7.01.16
8.01.48
9.02.1
Octagon
Dimensions (mm)Weight (ct)
4 × 30.18
5 × 30.25
6 × 40.50
7 × 50.92
8 × 61.38
9 × 71.93
10 × 83.16
11 × 94.09
Square
Dimensions (mm)Weight (ct)
2.00.06
2.50.09
3.00.14
3.50.28
4.00.33
4.50.46
5.00.61
5.50.65
6.00.99
7.01.59

Sources

The main desposits (but also the most famous) are in Colombia, but beautiful emeralds can also be found in other countries

such as Zambia, Brazil, Zimbabwe, Madagascar, Pakistan, India, Afghanistan and Russia.

Common treatments

The most common treatment is fracture-filling :

– using oil such as cedar oil or sweet almond oil, waxes or colorless resins

– using coloured oils to enhance the gemstone colour (coloured filler materials can also be considered as dyes as it changes the gem colour)

– using synthetic resin such as epoxy

Fracture-filling improves the apparent clarity of a gemstone by making its fractures less visible

Most laboratories provide informations on the amount of filler material present in the gemstone (minor, moderate, major).

However few will confirm the type of filling material (such as the French Laboratory of Gemmology (LFG), and Gem Paris).

Care and cleaning

Emeralds can break easily and should not be exposed to mechanical shocks.

Keep away from solvents that may interfere with the filler materials,

but also heat that could make included stones break or dry their filler out.

You should also avoid detergents, ultrasound and steam jets for same reason.