The colour of a diamond starts with the letter D, why not A? Well the powers that be thought that if a finer colour was ever found they would give it an A grade. To date the finest diamonds ever mined have been D colour.
D-E-F Colourless, by this we mean the diamond is pure white.
G-H-I Near colourless, generally only a trained gemmological can tell the difference
J-K Very slightly tinted, a small hint of yellow
L-M Faint yellow/brown
N-Z slowly graduating to a deeper yellow/brown
All diamond clarities are graded using x10 magnification. Only a tiny minority of diamonds mined today would be internally-flawless or flawless. The vast majority of diamonds will have small inclusions.
FL/IF No visible inclusions
VVS1-VVS2 Very very slightly included
VS1-VS2 Very slightly included
SI1-SI2 Slightly included
I1 Included slightly visible to the naked eye
I2 More included visible to the naked eye
I3 Heavily included to the naked eye
Diamonds are cut in a multitude of shapes including specialist cuts and even animals. The cut generally refers to the quality of how the diamond has been polished which will affect the way the diamond distributes light and in turn sparkles. In addition to the cut the symmetry is taken into account.
Carat is a measurement of weight and not as many people think a measurement of size.