Four C's Of Grading Diamonds
Carat
The carat size is in fact the weight of the diamond. Different shape stones with different proportions may well have the same carat weight and the cut of a diamond with its proportions will ofter determine the better stone in terms of the way it looks
Cut
The cut of the diamond is not its shape it is to do with its symmetry, the proportions and ratio of the upper stone (the crown) to the lower pointed part (the pavillion) . Other factors such as the girdle width may well determine the overall quality of the cut and the diamond.
Clarity
The clarity of the stone relates to its internal characteristics and will range from an internally flawless stone to one that had a number of flaws know as inclusions . Flaws that can be seen with the naked eye would be material and will reduce value significantly and may impact the durability of a diamond. Good quality diamonds may well have inclusions but these are more normally only seen with a 10 times loupe (Jewellers' magnifying glass). There is a standard clarity range starling with IF (internally flawless) ranging through :
VVS (1or2) : very very slightly included
VVS (1or2) : very slightly included
SI (1 or 2): slightly included
Diamonds graded I (included) or P will of lesser quality and these might reflect a durability issue
Colour
Colour is more often determined by the International standard (GIA) starting at "D" (totally colourless and through the alphabet until colour begins to be detected (colour J) at colour M and beyond a stone may be considered tinted (usually a yellow tint); Beyond the alphabet colour range a diamond will find itself within the "Fancy" colours.