THE
4C'S
CARAT
WEIGHT
COLOR
GRADE
CLARITY
GRADE
CUT
GRADE
#1
CARAT
Carat is a measurement of WEIGHT, not SIZE and so the overall diameter (mm) could differ slighter larger or smaller even though the carat weight is correct
The letters in the D to Z scale don't describe actual colors, or hues. Each letter actually represents a range of color that's based on a combination of tone - darkness or lightness - and saturation - intensity. It's measurable of how noticeable a color is. In the normal range, the closer a diamond gets to colorless, the higher its per-carat price. There's an especially large leap in the price of the colorless diamond, which is extremely rare.
#2
COLOR
#3
CLARITY
Diamonds have internal features, called inclusions, and surface irregularities, called blemishes. Together, they're called clarity characteristics. Clarity is the relative absence of inclusions and blemishes.
#4
CUT
A well-cut diamond can make light perform in breathtaking ways, resulting in a magnificent display of three important attributes: brilliance, fire and scintillation.