Carat Weight
The weight of a diamond is measured in carats. One carat equals 0.20 grams and is divided into 100 points. Thus a diamond of 0.25 carat could also be described as a 25-points diamond.
However, a diamond’s value is not determined by weight alone. A small Hearts & Arrows diamond is more brilliant than a large diamond with inferior colour, clarity and cut.
Colour
Each diamond is colour-graded from “D” to “Z” where “D” is totally colourless and “Z” is light yellow.
Due to a diamond’s high brilliance and dispersion of light when looking through the diamond’s table or crown, colour grading should be determined by examining the diamond through the side of the pavilion but not looking at the top.
To determine the colour, a diamond is placed face down and compared to an internationally accepted master set of stones under controlled lighting and precise viewing conditions.
Colorimeter will also be used to increase the reliability and accuracy of the colour grading of diamonds.
Clarity
Virtually all diamonds have natural characteristics. Clarity refers to the presence of tiny natural characteristic inclusions within the diamond, and/or on the surface of a diamond.
The clarity of a diamond is graded by experienced gemologists under 10 times magnification.
Considerations in grading the clarity of a diamond include the number, size, brightness and location of the internal and external characteristics.
