Jewellers
9 Tranquil Vale Blackheath London SE3
Tel/ Fax: 020 8852 0181
multi map location.
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
Finished Diamonds
A finished diamond is usually characterised by four characteristics namely carat, cut, clarity and
colour. This is generally referred to as “The 4 C’s”.
Carat Weight
A diamond's size is measured in carat weight. The larger a diamond, the more rare it is.
- Each carat is equal to 100 points.
- A .75 carat diamond is the same as a 75-point diamond or a 3/4-carat stone.
clarity, cut, and colour.
Clarity
Almost all diamond have some kind of flaw to their perfection. The extent of the flaw will affect the
beauty and therefore price of the stone. Good cutting can remove some in the transition from
rough to cut, but some will always have to remain. Codes are used by the industry to describe the
extent of the flaws, below you can see a listing of the codes in descending price order:
IF - Internally Flawless - No internal flaws. Very rare and beautiful diamonds which are quite
expensive.
VVS1, VVS2 - Very, Very Slightly Included: Very difficult to see inclusions under 10x magnification.
An excellent quality diamond.
VS1, VS2 - Very Slightly Included: Inclusions are not visible to the unaided eye. Less expensive
than the VVS1 or VVS2 grades.
SI1, SI2 - Slightly Included: Inclusions are visible under 10x magnification, SI clarity diamonds are
usually of the best value since inclusions are not visible to the naked eye and prices are
reasonable when compared to prices of the VS2 clarity and up grades.
SI3 - Slightly Included-EGL: SI3 is an EGL grade and is not recognized by GIA or other
gemological institutions. It may be graded by GIA as either SI2 or I1. SI3 diamonds never have any
black inclusions or cracks visible to the naked eye, but may have some very minor white inclusions
which can be seen with the naked eye.
I1 - Included: an I1 clarity diamond will have a visible flaw which can be seen with the naked eye,
but there should only be one major flaw which is not too obvious. If your budget only allows for an
SI3 or I1 clarity diamond, be sure to examine it thouroughly before purchasing and make sure you
can not see any inclusions.
I2, I3 - Included: These diamonds will have inclusions visible to the naked eye, and will have many
black spots from the black inclusions and appear cloudy from the white inclusions, feathers and
cracks.
There are many different types of flaws. The best way to become acquainted with them is to look
at lots of diamonds. The more common ones are as follows:
Pinpoint: A very small white dot on the surface of the stone. By far, the most common flaw
Carbons: A very small black dot on the surface of the stone. Less common than pinpoints
Feathers: Small cracks within the stone, similar in look to broken glass. Small internal feathers
are harmless (other than lowering the clarity rating of the diamond), but large feathers can
become a problem because the crack can grow as the diamond ages
Clouds: Hazy areas within the diamond, actually made up of many small crystals that are
impossible to see individually
Crystal Growth: A small crystalline growth within the diamond. Looks like a small diamond within
the big diamond
Colour
The purer a diamond's colour, the rarer it is. Diamonds are graded by colour, starting at D and
continuing through the alphabet. While many diamonds appear colourless, they may actually have
subtle yellow or brown tones. Although still beautiful, they will be less rare and therefore less
valuable.
To appreciate the simple beauty of each individual stone, you should compare diamonds side by
side with a jeweller.
"Fancy" diamonds -- in well defined colours that include red, pink, blue, green and canary yellow
-- are highly prized and particularly rare.
Cut
A well cut or faceted diamond, regardless of its shape, scintillates with fire and light -- offering the
greatest brilliance and value.
While nature determines a diamond's clarity, carat weight and colour, the hand of a master
craftsman is necessary to release its fire, sparkle and beauty. When a diamond is cut to good
proportions, light will reflect from one mirror-like facet to another and disperse through the top of
the stone, resulting in a display of brilliance and fire. Diamonds that are cut too deep or too
shallow lose light that spills through the side or bottom. As a result, poorly cut stones will be less
brilliant and beautiful -- and certainly less valuable -- than well cut diamonds.
Rough Diamonds
All of those in the rough diamond business must have an understanding of how to price rough
diamonds. The ultimate pricing comes from its derivative, the finished polished diamond.
Buyers of rough diamonds must be particular aware of the prices of rough. If you purchase the
rough diamond without knowing the exact price for that rough diamond and you overpay, there is
NOTHING that can be done to recoup your loss.
One cannot tell you how many people come to us to sell their rough diamonds and I ask them how
much they want for the parcel and the amount they come back with is so outrageous that it would
be cheaper to by the equivalent finished diamonds. After asking them why they are asking so
much they explained to me, that is what we paid for it. Well here is the big problem over and over
again. Once you over pay for the rough you are and will be in a losing position that you cannot
get out of. You will take the LOSS.
Even if you are trained in rough diamonds you need to keep up with the changing rough diamond
price environment. The same story above works in reverse as well. If you are not aware of the
rising prices of rough you will lose out by not paying or offering enough for the particular parcel
and you will not own the parcel in which you could have made a nice profit.
The next most important part of purchasing or selling rough diamonds is to know the four basic
structures (crystals):
Octahedron-Sawables: This structure will yield approximately 50 percent in the finished diamond.
There are two methods of cutting this type of structure. The first is to cut the octahedron in half to
yield two equal finished stones. The second method is to top the octahedron to yield one larger
stone and one smaller stone. The maximum topping procedure would be 65/35 percent. The
reason for doing this is to obtain a larger finished stone, which would increase the total value of
the combined finished total. This method is very dependent upon the thresholds achieved in the
finished pricing guides.
Whole Stones: This crystal will yield between 35-45 percent. The yield will vary depending upon
the physical dimensions of the crystal. You should be careful not to judge a whole crystal that is
flat in structure because the yield will drop to 25 percent.
Flat, Cleavage, Macles: These structures will yield approximately 25 percent in the finished
diamond. As mentioned above, be careful not to grade these structures as a whole stone.
Formation In The Earth
Diamond is a polymorph form of carbon. The other form is graphite. For carbon to turn into
diamond, 3 factors are needed: time, very high temperature (around 1,000 degrees) and very
high pressure above 30 kilobars (kb). The Pressure and Temperature conditions within the earth,
are known as geotherms. Any changes of « P » (Pressure) and « T » (Temperature) within the
environment where diamonds are formed, may reverse the cycle back to graphite or gas. The
main bearing diamond rocks are kimberlite (the name proposed by Lewis in 1888 is for the
Kimberley district in South Africa), eclogite, lamproite. Diamonds can be formed going down
towards the mantle of the earth (subduction), going up towards the surface of the earth
(obduction) and also on impact (meteorites).
The most common shape of kimberlite pipe is « the carrot shape » it also occur as dykes and
rarely as sills. Within the kimberlite pipe 3 zones are recognized, the crater, diatreme and the root
zones. The pipes do vary in size, up to 200 hectares. In contrast to kimberlites, which may show
some vertical flaring over 1 to 2 kms, Lamproite bodies are shallower, around 0.5 kms in depth .
Many lamproites have a champagne glass shape craters. The difference between kimberlites and
lamproites pipe shapes has important implications for exploration (ore volume calculations).
Diamonds in meteorites were discovered in Arizona or South Pole and they contained minuscule
crystals of diamonds. In 2004, The Harvard-Smithsonian Center for Astrophysics has announced
the discovery of a mass of crystallized carbon formerly known as star BPM 37093, now known as
the biggest diamond in the galaxy, fifty light years away from Earth in the constellation Centaurus.
The diamond is estimated to be 2,500 miles across and weighs approximately 10 billion-trillion-
trillion carats – a one, followed by 34 zeros = 10,000,000,000,000,000,000,000,000,000,000,000
carats.
Priamary Deposits
Diamantiferous kimberlite/lamproite pipes are the « Primary deposits ». Diamonds are transported
to the surface of the earth by the magma pushing upwards the kimberlite (diamond bearing rock )
at great velocity. When it reaches the surface, the volcanic eruption occurs releasing an
enormous energy creating the birth of the volcano. The material blown out from the explosion
probably landed in a pile around the vent. The material eventually washes away by rain or washes
back into the central zone of the crater or is dispersed by other weathering processes. The
kimberlite that remain in the cracks of the earth crust crystallize as dykes.
Secondary Deposits
The secondary deposits are formed by the weathering of the kimberlite and the lamproite. The
diamonds are released from the rock and then, they are transported hundreds of kilometres away
to be found in river beds, beach sands, old river beds (sometime found on top of hills deep jungle
forest, deserts, etc... Diamonds may also have been transported by glaciers and if the journey
has been hard, rough and long, they are not to be found as they have been broken and grinded
into near dust
Principal Crystaline Shapes
Diamond crystallizes in the cubic system and its crystalline shapes are thus numerous, the
principal ones are: octahedron, cube, dodecahedron, rhombododecahedron and trioctahedron
After diamond was recovered, it will have to be sorted according to certain categories before
being sold:
- Diamonds for cleavage.
- Diamonds for sawing
- Diamonds for cutting.
- Industrial diamonds.
Rough diamond can be sorted according to 3 distinct categories:
- Gem quality.
- Industrial quality.
- Crushing-boart or boart.
Only 20 % of the world production of rough diamonds are intended for the jewellery (gem quality)
and 80 % for the industrial uses. There would be more than 5,000 possible rough diamond
classifications
It is this type of quality which will be used in the jewellery industry. It must be of good colour and of
good clarity, its shape is not very important because the diamond must be cut. This category of
diamond requires a classification of the stones by subcategories:
- The stones: very beautiful stone of more than 1 carat.
- The fancy colours stones are those with colour that does not lies between the bluish white
and the yellowish. - The colour of fancy colours diamonds is blue, green, pink, yellow, brown, etc...
- The closed stones: are monocrystals, beautiful shapes, good for sawing and polishing.
- The spotted stones: are monocrystals, beautiful shapes, these stones have inclusions but
it is possible to make them disappear with the cutting. - The naats: are deformations of crystallizations, they must be cleaved or bruted.
- The irregular stones: are octahedral or dodecahedral (irregular shapes), they are directly
cut. - The cleavable stones: they must be cleaved.
- The coated stones: the industry have named coated stones « speculation stones ». A
gangue or a film covers them hiding the interior of the stone. They can remain opaque or
let appear a beautiful stone. - The frosted stones: are identical to coated, but the film is translucent.
- The milky stones: as its name indicates, this stone has a milky aspect.
- The sands: they are very small stones (less than 0.10 carat), mostly used for the size 8/8.
- The plats: in fact generally macles are very often employed for the rose cut.
Cutting.
The 5 operations necessary for the transformation of rough diamond into a cut diamond are as
follows: cleaving, sawing, bruting, cross working and brillianteering.
The transformation of a octahedron rough diamond (top line) and a dodecahedron rough
diamond (line below) into a cut diamond.
Cleaving
Not all rough diamonds needs to be cleaved or sawed. Some rough diamond are well formed and
can be considered ready to be cut. In order to remove any impurities or irregularities in the
diamond, a rough diamond is placed in a quick-drying cement. A sharp groove is then carved into
the diamond, using another diamond or a laser, along the plane of weakness. Then, a steel blade
is placed in the groove and a sharp blow to the blade is applied spliting the stone. The diamond is
then removed from the cement.
Sawing
Sometimes, diamonds have to be cut against a cleavage plane, which cannot be done by
cleaving. Using a phosphor-bronze blade rotating at about 15,000 rpm, the saw slowly cuts
through the diamond. Lasers are also being used to saw diamonds.
Bruting
This procedure is performed only for diamonds that to be finished as round, brilliant stones (fancy
shaped stone require a different type of preparation). The diamond is placed in a lathe, and
another diamond in the lathe is rubbed against it to create the rough finish of the girdle.
Brillianteering.
The function of brillianteers is to cut and polish an extra 40 facets onto the already polished facets
done by the cross-workers, in order to create a round brilliant cut diamond with 58 facets that will
unlock the full brilliance and fire of light being reflected by the polished diamond.
The Kimberly Process
The United Nations Security Council has imposed sanctions on the rebel movements in Sierra
Leone and Angola and on the Liberian government for supporting the rebels in Sierra Leone. The
sanctions include a prohibition on imports of rough diamonds from Liberia and, if they are not
accompanied by a certificate of origin issued by the respective legitimate governments, from
Angola and Sierra Leone.
The sanctions have failed to stop the flow of conflict diamonds into the legitimate trade or to bring
the conflicts to a halt. Conflict diamonds are continuing to find a market and enter the legitimate
diamond trade. There is therefore a need to complement the sanctions to reduce the role of such
diamonds in fuelling conflicts.
At the initiative of African diamond producing countries in particular, producer and trading
countries, industry and civil society have met in the «Kimberley Process» to design a certification
scheme for the international trade in rough diamonds.
The purpose of the scheme is to prevent «conflict» diamonds from fuelling armed conflicts and
discrediting the legitimate market for rough diamonds, which makes an important economic
contribution, not least to certain developing countries in Africa. Such a certification scheme will
make a major contribution to bringing an end to these conflicts and serve the implementation of
the EU programme on conflict prevention.
The certification scheme is basically an export and import control regime. Producer countries will
control the production and transport of rough diamonds from mine to point of export. Shipments of
rough diamonds will be sealed in tamper-resistant containers and a Kimberley Process certificate
issued for each shipment. Importing countries will inspect the seal and the certificate at the time of
import. Imports of rough diamonds not accompanied by a certificate issued by a Kimberly Process
participant will be prohibited, as will exports to non-participants.
The Community’s participation in the Kimberley Process certification scheme for rough diamonds
is necessary and desirable for foreign and security policy reasons and economic considerations.
In Antwerp and London the Community has two of the world largest rough diamond trading
centres, and these centres are vulnerable to the effects of conflict diamonds on the legitimate
trade. Participation in the certification scheme will protect the economic and financial interests of
those centres and the Community as a whole.
If you want more information, you can visit the European Commission website. You can download
the Kimberley Process Regulation on their website.
