Pleochroïsm : distinct (green, green-yellow to green-blue)
Cut :
The colouring of emeralds is due to the presence of chromium and vanadium.
In general, the emeralds are not transparent (except for some stones of great quality): there are often inclusions (liquid, bubble of gas, other crystals,…). If these inclusions do not take much place, they are not regarded as defects, giving them even a seal of authenticity beside to synthetics emeralds.
The value of an emerald is not judged only on its purity but also on its color: A stone having inclusions but of a deep green color will have more value than a pure stone but of a too pale green !
It should be known that the way in which one cuts the stone influences its color :
- cut of the table perpendicular to the axis of the hexagonal prism : green-yellow
- cut of the table parallel with the axis of the hexagonal prism : green-blue
In principle, the lapidary will try to obtain the maximum mass of the crystal and not a specific color.
History :
Emerald takes from Greek “smaragdos” meaning “green stone”. At old times, almost all the green stones were called emeralds.
The most famous emeralds are :
Topkapi Palace in Istambul (16 300 cts)
Mineralogical Museum in Moscow (11 130 cts)
Treasury of Vienna (ointment flask of 2 200 cts)
British Museum of London
Imperial treasure of Iran
American Museum of New-York
Deposits :
The countries having deposits are :
Country
Quantity
Quality
Comment
Colombia
Important
Some stones of higher quality
Mines worked by Inca
Brazil
Important
Ordinary stones
Zimbabwe
Crystals of small size but of good quality
South Africa
5% of good quality
Ural
Weak
Good rare quality
India
Weak
Pakistan
Weak
Australia
Weak
United States
Weak
Egypt
Null
Mines of Cleopatra
Austria
Very weak
Unsuited crystals for the cut (but with a beautiful color)
Emerald
