They aren t exact because of the way diamond cutter s cut the stone.
Ideal cut diamond dimensions.
The tolkowsky ideal cut.
But the more a diamond is within super ideal cut proportions the better the light performance will be.
If you can obtain the above super ideal proportions without compromising on the other 3cs it would be an ideal scenario.
In 1919 the mathematician and renowned gemologist marcel tolkowsky published his findings for the perfect diamond proportions in his thesis entitled diamond design a study of the reflection and refraction of light in a diamond all diamonds that were within the parameters of the so called tolkowsky ideal cut were considered to have an excellent light return.
While cut is absolutely critical the brilliance of a diamond is about all 4cs not just cut.
In tolkowsky s initial publication he stated that the ideal cut diamond should only have a table proportion of 53.
However don t compromise overly on the other 3cs in order to get the best proportions.
For example see this excellent emerald cut diamond with a 64 6 depth.
For example this beautiful 1 01 carat oval cut diamond has a depth of 65 8.
This means you are able to buy a larger carat size diamond for less money and get a bigger bang for your buck.
So cut is often compromised.
If a diamond is only slightly outside of super ideal cut proportions it will not matter that much.
Nobody can agree on a set of numbers that will accommodate every cut and shape of stone.
Compared to round cut diamonds the prices of oval diamonds are generally 20 30 lower due to a better yield on rough cutting.
For an oval cut diamond an ideal depth is less than 68 percent.
They strive to maintain carat weight and quality whenever possible.
Tolkowsky s standard for ideal cut diamonds called for a total depth of 59 3 with a table diameter of 53 and a crown angle of 34 5 degrees which is offset by a pavilion angle of 40 75 degrees however apparently he never accounted for the girdle edge of the diamond.
