Diamond
is named from the Greek ‘adamas’, meaning unconquerable, an early
recognitionon that it is the hardest of all natural minerals. This
supreme hardness is combined with exceptional luster and dispersion,
giving diamond the lasting fiery brilliance for which it is prized.
It is
perhaps difficult to believe that diamond, like graphite and charcoal,
is as form of carbon. Diamond crystallizes in the cubic system, at
enormous pressures and high temperatures. Its exceptional properties
arise from the crystal structure, in which the bonding between the
carbon atoms is immensely strong and uniform.Much diamond occurs as well
– formed crystals ,most commonly as octahedral. Graphite, which has a
hardness of 1 to 2 on Mohs’ scale, consists of weakly bonded sheets of
carbon atoms. Charcoal is non – crystalline.
Diamond
is the most intensively mined and carefully graded of all gem
minerals.The quality of a gem diamond is assessed by a system known as
the ‘ Four Cs’ : colour, clarity, cut and carat weight. Diamond varies
from colourless, through a range of yellows and browns, to green, blue,
pink and a very rare red. Colourless diamonds or fancy coloured diamonds
(those strong or unusual colour) are considered the most valuable. Truly
colourless stones are rare as most diamonds are tinged with yellow or
brown, by impurities. The most common impurity is nitrogen, which given
rise to brown, yellow, green and black diamonds, depending on the amount
present and its distribution in the crystal structure. Blue diamonds
contain minute traces of boron.
Clarity
is judged on the extent of mineral inclusions and flaws, such as
cleavages, visible at X 10 magnification. Inclusions can affect the
commercial value of gemstones either by reducing clarity or by providing
valuable information about the origin of a gem.
Studies
of some garnet and pyroxene inclusions, coupled with a knowledge of the
conditions needed to synthesize diamond, reveal that many diamonds
formed at depths greater than 150 Km underground.
The cut
is of supreme importance in displaying the full beauty of a diamond.
Although diamonds were known in India 2300 years ago, crystals were not
cut for many centuries because it was believed that diamond had magical
properties and that there would be lost if the diamond was cut.In
Europe, the polishing of simple point and table cuts from octahedral
crystals, and rose cuts from cleavage fragments, began sometime 1300.
The popularity of diamond has grown with the development of the
brilliant cuts, which best display the fire in diamond.
Although
early versions appeared in the 17 th century, the modern form of this
cut was set in 1991, when Marcel Tolkowsky published ‘ ideal
dimensions’ for a brilliant - cut diamond.
Today
lasers are used to cut diamond, but the only mineral that can cut a
diamond is diamond and grinding and polishing are carried out by a
lapidary using powdered diamond.
This is
only possible because diamond is less hard in certain crystal
directions. Diamond also cleaves relatively easily, in four directions
parallel to the octahedral crystal faces, so cleaving is sometimes used
to divide large crystals and to trim away flawed material.
For over
2000 years, diamonds were found only as eroded crystals in river
gravels. Until 1725 India was the major source of diamonds, with much
smaller amounts mined in Kalimantan (Borneo).Diamonds were then
discovered in Brazil, which became the leading suppliers as Indian
production waned. South African diamonds were found first in 1867, in
gravels near the Orange River.
Further
exploration in the Kimberley region of South Africa revealed volcanic
pipes filled with a hitherto unknown rock type which contained diamonds.
The rock, a variety of peridotite, was named kimberlite and was
recognized as the diamond source of rock. This discovery formed the
basis of the huge modern diamond industry. Many similar pipes have
since been found in other African countries, in Siberia, China and more
recently in the Northweste Territories of Canada. A closely related
rock type , lamproite,is the source of Western Australian diamonds.
Diamond
possesses many interesting properties in addition to its supreme
hardness, luster and fire. Diamond’s attraction to grease and its blue
fluorescence under X – rays is exploited in recovering diamond from the
host rock. Many diamonds also fluoresce in ultraviolet light, and the
variable nature of this fluorescence provides an interesting means of
identifying jewellery set with diamonds.
|
COMPOSITION |
Silicate -
Mg3Al2 (Sio4)3 |
|
CRYSTAL SYSTEM |
Cubic
|
|
HARDNESS |
7 - 7 .5
|
|
SPECIFIC GRAVITY |
3.5 - 3.8
|
|
STREAK
|
White
|
|
LUSTRE
|
Vitreous
|
Diamond
Rough High Grade Quality for Making faceting cut.
Smaller pieces size
0.1 grams to 1 grams
Larger Pieces 1
gram to 5 grams
Minimum Order Supply - 0.5 carat
Maximum Order Supply - 100
Carats
PRICE : SEND US AN EMAIL FOR THE
QUOTATION.
sales@seabgems.com
