The Diamond 4C's
The main diamond cuts are:
|Round Brilliant||Emerald Cut||Princess Cut||Heart Cut|
|Oval Cut||Marquise Cut||Pear Cut||Round Brilliant|
Popular diamond cuts include Heart, Emerald, Marquise (Oval with pointed ends), Oval, Pear, and Princess. There are unusual cuts appearing all the time such as the J C Millennium which is basically a Round Cut stone similar to the Round Brilliant, and the Radiant Cut which is an octagonal stone similar to an Emerald or Step Cut with upper girdle facets similar to the Princess Cut which is a square stone.
Cut The most popular cut is the modern round brilliant (R/B):
Round Brilliant Facets
The standard brilliant comprises:
1 Table facet
8 Star facets
8 Kite or Upper Main Facets
16 Upper Girdle facets
Total facets: 33 Crown Facets
This is the waist band in the middle, and is sometimes faceted.
16 Lower Girdle
Total facets: 25 Pavilion Facets
Thus there are 58 facets in total.
There are many differing scales used by different organisations for color, but the most common one is an alphanumeric scale starting at the color D. This is the whitest color exhibited by diamond. To give you a feel for the colors we have prepared a table below:
|D||Pure White - the most prized color|
|E||Exceptional white - colorless group|
|F||Excellent white - colorless group|
|G||Good white - colorless group|
|H||White - colorless group|
|I||Slightly tinted white/ white when viewed from top|
|J||Slightly tinted white/ commercial white|
|K||Tinted white/ still acceptable white when mounted|
|L||Tinted white/ needs yellow setting to look its best|
|M||Slightly yellowish/Tinted color-champagne|
|N||Slightly yellowish/Tinted color-champagne|
|Clarity:||Number and Size||Expert-10x loupe||Naked Eye||Influence on Brilliance|
|IF||no inclusions-internally flawless||nothing||nothing||none|
|VVS1||very very small inclusions, pin pricks||very difficult||nothing||none|
|VVS2||very very small inclusions, pin pricks||very difficult||nothing||none|
|VS1||very small, still minute||difficult to see||nothing||none|
|VS2||very small, still minute||difficult to see||nothing||none|
|SI2||tiny||easily seen||nothing from top||none|
|I1||small||recognisable immediately||difficult to recognise||none|
|I2||larger and/or numerous inclusions||obvious||recognisable immediately||slight|
|I3||large and/or numerous||very obvious||very easily recognised||heavy influence|
Clarity is an indication of a diamond's purity. It describes the degree to which a diamond is free of imperfections. The internal clarity grades range from internally flawless (IF) to fairly included (I3)or third pique (pronounced peekay) also written P3.
Flaws in diamonds may include external blemishes (from naturals and polishing defects) and internal inclusions. Most blemishes are so small as to have no affect on the beauty or brilliance of the stone. In nearly all diamonds, traces of minerals, gasses or other elements were trapped inside during the crystallization process. Inclusions look like tiny crystals, clouds, or feathers and are unique to every diamond. It is very rare to find a diamond that is completely clean to the expert eye using magnification.
The clarity of a diamond is graded by how many, how big and how visible the inclusions are, and where they are located within the diamond. The fewer and smaller the inclusions, the more rare and valuable the diamond. It is very rare to find an internally flawless (IF) diamond.
Grading according to discernability of inclusions:
It can be seen that diamonds graded SI2 and better will appear to be perfect, and no loss of brilliance will be detected. Combined with a good cut and color of H or better, we have a perfect diamond for any piece of jewellery.
Lasers have been used commercially for drilling diamonds since the late 1960's. It is possible to improve the appearance of diamonds which have dark magnetic pyrites and magnetite inclusions by drilling into the diamond surface and then bleaching out or chemically dissolving the inclusions with an etching fluid such as sulphuric acid and saltpetre. The drill holes are then usually filled with a highly refractive wax or synthetic resin and this protects the drill chanel against penetration of dust and dirt. This can be affected if your diamond is ever subjected to heat or acid as often is the case when being set in jewellery or worked on by an unsuspecting working jewller. Although the treatment is fairly permanent, we will not sell you a diamond that has been drilled.
This is a more recent enhancement by which inclusions and especially cracks which break the surface can be made more transparent and hence improve the clarity of a cut diamond. The cracks are filled under pressure (50 atmospheres) in a vacuum at high temperature (400 degrees Celcius) with a glass of refractive index close to that of diamond at 2.417. A color flash similar to that on the surface of a detergent bubble is visible due to the juxtaposition of the two different materials. Unfortunately the process though widely used is neither durable or permanent and will not withstand the cutting and repair processes involved in jewellery work. We will not sell you a diamond that has been filled.
Internet Shopping Precautions
The Internet is full of drilled and or filled diamonds, especially eBay! We strongly advise you to be extremely cautious when buying diamonds on the Internet auction sites.
The weight of a diamond and is measured in Carats. 1 Carat equals 0.2 gram and there are 100 points to a carat. Thus a 50 point diamond is half a carat (0.50ct) and weights 0.1 gram. A Grain, no longer used, is accepted to be 0.050 grams. Many dealers still use the terms a grainer meaning 0.25ct, two grainer - half carat, six grainer- 1.5 carats etc.
There is an approximate relationship between weight and diameter of a round brilliant cut diamond. This is useful when trying to estimate the size of a diamond.
|Weight: ||Size (diameter):||Weight: pts (diameter):||Weight: fractions |
Most diamonds are accurately weighed on an electronic scale to the nearest 1000 th of a carat (0.001). If a stone weighs 0.009 it is rounded up and 0.008 is rounded down. This is standard practice in accordance with diamond club rules, but in all other industries 5 is rounded up and 4 is rounded down.
Weight 2.329 carats will be described as 2.33 carats.
Weight 2.328 carats will be described as 2.32 carats
According to Trading Standards, jewellers are technically allowed to round up at the 5, hence 2.325 carats rounds up to 2.33 carats but this is frowned upon in the trade.
Where a diamond has been assessed by a laboratory it is termed a certificated or certified stone.
We sell diamonds issued with a EGL,GIA, IGI, AGS or HRD certificate, but other certificates may be available on request.