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The Four C's


Cut is the human contribution to a diamonds beauty, brilliance and fire. The way a diamond is cut can affect the other three C's which are dictated by nature. Even if the diamond has perfect colour and clarity a diamond that has been cut poorly will appear dull and lifeless. One of the factors that make a diamond so rare and special is its ability to display a unique fire and brilliance.

Diamond Cut Depth Diagram

The diamonds in this diagram would all weigh the same in carat weight, but appear quite different in shape; this is due to the cut.



Diamonds take in the light from the table (top) of the stone. When the stone is cut to the correct proportions it is able to reflect and refract light from one facet to another, properly.



If the diamond is cut to deep, some of the light escapes through the opposite side of the pavilion.



If the cut of the stone is too shallow, the light escapes through the base of the stone before it can be reflected. When the light escapes, the diamond does not scintillate and sparkle to its full capacity.

A classic round brilliant diamond has 57-58 facets, the diamond cutter must place each of the stones facets and angles, which act as light dispersing mirrors, in exact geometric relation to one another in order to bring out the stone's fire and brilliance.


There is a difference between the cut and the shape of a diamond. The shape is largely a matter of personal preference and is only limited by the skill and imagination of the craftsman. Two of the major cutting centres in the world are Antwerp and Israel. All of the diamonds available to you through Diamonds Forever NZ® come direct from these centres.


A well cut stone will dramatically increase its beauty and therefore its market value. When comparing prices, make sure you are not only comparing size, colour and clarity but also the diamonds cut.


There are 7 traditional shapes for diamonds.

Round Brilliant Diamond Princess Cut Diamonds Emerald Cut Diamond Oval Cut Diamonds
Heart Cut Diamonds Pear Cut Diamonds Marquise Cut Diamonds  


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When the carbon is compounding to create the diamond, if natural gasses enter through the stone as it is forming it will change the colour saturation, leaving traces of colour within the stone. Due to the effects of nature you would expect all stones to have some trace of colour within.


Diamonds with purer colour saturation have a greater capacity to reflect and refract light allowing greater brilliance. White diamonds come in various shades, with most having a barely perceptive yellow, grey or brown tint. The highest quality diamonds are described as colourless and are extremely rare and valuable.


Diamonds colour is graded on a letter scale beginning with D (colourless) and moving through the alphabet to Z. A single increase or decrease in the colour grade can make a price difference of thousands of dollars, depending on the size of the diamond.


With diamonds of "D" through to "Z" colours lined up in a row, the steady progression as the colours get deeper is easily seen. But generally, to the unaided eye, colour cannot be detected in a mounted diamond until well down into the K, L or M range.


Even experienced diamond graders have a difficult time distinguishing between any one colour grade. When purchasing a diamond don't take any chances. Always make sure the stone is accompanied by a certificate from a leading gemmological laboratory.


Colour Chart
Diamond Colour Chart
Near Colourless
Faint Yellow
Very Light Yellow
Light Yellow


Fancy coloured diamonds make up a small but exotic part of the diamond industry. These diamonds include red, blue, green and pink, as well as the stronger yellows. They also come in combinations such as orange/yellow or grey/blue. Red and green are the rarest fancy colours. These stones are expensive and quite rare.


Apparent colour can also be influenced by the tendency of some diamonds to react to the ultraviolet radiation in daylight and fluorescence light bulbs. Fluorescence grades of; faint, inert, negligible and medium can only be detected by a trained gemmologist. A Fluorescence grade of strong or very strong can make a diamond with a near colourless grade look even whiter yet in some instances give the diamond a slight hazy or oily appearance. Diamonds with strong or very strong fluorescence are priced slightly lower than other diamonds.


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The greater the clarity of a diamond, the more brilliant it appears. Almost all diamonds contain minute traces of non-crystallised carbon or small non-diamond crystals.

These are called inclusions and may be interior or exterior inclusions. Flawless diamonds are extremely rare and valuable because the fewer the inclusions in the stone, the less interference with the passage of light through it and the greater the sparkle.


Most diamonds contain blemishes on the outside of the diamond or inclusions trapped inside the diamond. Your jeweller scrutinizes each diamond under a 10-power magnification to view any flaws. Small inclusions will probably not be visible to the naked eye and are unlikely to mar the stone's beauty.


Clarity Grades range from Fl (Flawless) for a perfectly clean diamond, even under 10-power magnification, to an I3 stone where the diamond is so full of inclusions it is both ugly and breakable. The cleaner the diamond the rarer and more expensive it will be.

Clarity Grade Description
No internal or external flaws.
Internally Flawless
No internal flaws, slight external blemishes.
Very, Very Slight Inclusions
Very difficult for a professional to see under 10X magnification.
Very Slight Inclusions
Difficult for a professional to see under 10X magnification.
Slight Inclusions
Easy for a professional to see under 10X magnification, might be visible to the naked eye.
Inclusions are visible to the naked eye.


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Carat Weight

Bigger is not necessarily better. A carat is a term referring to the weight, not the size of the diamond. One carat is equal to 100 'points', so the weight of a diamond of 50 points is 0.50 carats, or half a carat.


The carat weight of a diamond alone is meaningless, as a large stone is not particularly valuable if it lacks high-grade colour, brilliance and purity. In fact, sometimes stones may be poorly cut to maintain weight at the expense of quality. But large diamonds of equal quality to small diamonds are more valuable, as larger stones are rarer.


0.5 Carat
0.75 Carat
1.0 Carat
1.5 Carat
2.0 Carat
0.5 Carat 0.75 Carat 1.0 Carat 1.5 Carat 2.0 Carat


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