Gemmology

The 4 C's - Cut, Clarity, Colour & Carat Weight

Almost every jeweller will be able to tell you about the 4 C's which affect diamond prices. De Beers who run the Diamond Promotion Service pump out information to all jewellers about their famous 4 C's, the four factors which affect diamond prices. The Diamond Promotion Service wants you the consumer to be aware of the different diamond qualities, for better quality diamonds.

Sadly, a few jewellery shops can't or won't tell you about the 4 C's. Our advice is to avoid such shops. There is an important distinction between a jeweller and a jewellery shop, we are sure you can work that out for yourself. 

The Four C's Are:-

Cut
Colour
Clarity
Carat Weight

Cut
Cut - a short word with a lot of meaning.
Not all jewellers know what they mean when they talk about "cut" or that the word can be used quite ambiguously to mean at least two different things.
Cut can be use to mean:

 Shape

Shape would be a more accurate word rather than "cut" when we are talking about whether a diamond is round, square, oblong, or whatever. Some round shapes may have different arrangements or numbers of facets.


RoundThe most popular "shape" of diamond remains the round shape, for very sound reasons. Round shaped diamonds come in several varieties;


Modern Brilliant Cut
Often known as the brilliant, round, round brilliant, or "brill.". Has 58 facets, including the table and cult.


Eight Cut or Single Cut
Often used for very small diamonds, under 1 or 2 "points". These only have eight facets on the crown, eight on the pavilion, plus the table and culet, making 18 in total.


Old Cut or Early Modern Brilliant
An older, less precisely cut version of the modern brilliant cut.


Swiss Cut
Halfway between a brilliant and an eight cut, with 34 facets in total.


Rose Cut
Most rose cut diamonds are round, but some may look triangular, or have straight edges. Rose cuts look like diamonds which have been cut upside-down, they rise to a point at the top, and are often flat at the base.


Chips or Chippings
Chips should only be used to refer to deep fried potato fingers, french fries or pommes frites. To the French, chips mean potato crisps. Any jeweller who refers to chips or chippings meaning small diamonds is not a jeweller. Technically, we suppose that broken pieces of unpolished diamond could be set into jewellery, but we have yet to see it. Only refer to diamonds as chips if you don't mind folk realising that you don't know your crown from your culet!


Square
The square shaped diamond is really only a special case of the oblong shape.


Oblong
Most oblong diamonds are "step" cut, which means that their facets have been cut in steps, parallel to the edges, in the manner of a pyramid with its top chopped off. Long thin oblongs are often known as baguettes. Tapered baguettes also exist.


Emerald or Octagon
This is another "step" cut, but with the four corners mitred. This is done largely to protect the stone, as any sharp points are vulnerable to getting chipped.


Oval
Most oval diamonds are like a squashed round brilliant. Because their depth to diameter ratio varies, they can never be a "perfect" proportion, and therefore lose some brilliance when compared with a round diamond. Actually most "round" diamonds are very slightly off-round.


Marquise
Marquise or navette shape is like a long oval which has been stretched out to a point at each end. Similar comments apply as to the oval.


Triangle
Not a popular shape. It is normally a variation of the square cut, in that its facets are step cut, but some triangle shapes are a modification of the round brilliant cut.


Pear
One half oval, and the other half marquise.


Heart
Pear shape with a notch cut into the top.


Princess
A relatively new shape, oblong, usually square or almost square, but with a modified brilliant cut arrangement of facets instead of a step cut. This produces a much more brilliant and sparkly diamond than a traditional step cut square or oblong. It is not as successful for baguette shapes (long and thin).


Radiant

This is a hybrid cut, a cross between a princess cut and an emerald cut. It combines the best features of the round brilliant cut, the square shape of the princess or square baguette cut, and the cut corners of the emerald cut. Like the princess cut, it is normally used for near-square stones rather than oblong ones.