Ultimately, diamonds are sold by weight, but the other 3 factors are important too.
The strongest determining factor though, in the value of your gem stone, is the "Carat Weight". The actual weight of the stone is measured by a gemologist using a gem stone scale and the gem stone scale provides the weight of the stone in carats (not grams or ounces).
The following information is intended to help make you an "Informed Buyer" so that the decision you make and the stone you buy will be the best decision and the best stone possible. It is my sincere wish to help guarantee and optimize your future and continued satisfaction and happiness.
May you find this information useful in your diamond adventure and, please, feel free to visit me any time at my jewelry store should you wish to pursue these or other topics of interest regarding precious metals and precious stones and I will be happy to assist you in every way I possibly can.
Ken Gray
Owner and Proprietor of Design Jewelers
The importance of a diamond's "CUT".
A well proportioned (cut) diamond brings out the maximum beauty. Diamonds cut too deep or too shallow lose light through the side or bottom, resulting in loss of brilliance.
Good Proportions are Key
Most gemologists agree that the best cut diamonds are those that follow a set of formulae calculated to maximize brilliance. These formulae can be seen in a diamond's proportions, most importantly how the depth compares to the diameter, and how the diameter of the table compares to the diameter of the diamond.
TABLE
This is the large, flat top facet of a diamond.
CROWN
The upper portion of a cut gemstone, above the girdle.
GIRDLE
The narrow rim of a diamond that separates the crown from the pavilion. It is the largest diameter to any part of the stone.
PAVILION
The lower portion of the diamond, below the girdle.
It is sometimes referred to as the base.
CULET
The tiny facet on the pointed bottom of the pavilion,
which is the portion of a cut gem below the girdle.
DEPTH
The height of a gemstone, from the culet.
The best, most beautiful color for a diamond is no color at all. The Gemologist Institute of America has created a scale to measure diamond color, ranging from D (colorless) to Z (yellow).
The majority of diamonds sold are in the F to H color range.
Select an "eye-clean" diamond - one that has no imperfections visible to the unaided eye. An excellent value are the VS1 through SI12 clarity grades.
Frequently, inperfections in diamonds graded Slightly Included (SI) and Very Slightly Included (VS) are not visible to the unaided eye, making them an excellent value.