Diamond Cut Evaluation Index Advisor

Diamond Cut Evaluation Index Advisor


Our exclusive Diamond Cut Evaluation Index is designed to rate round ideal cut diamonds certified by the GIA. The calculation evaluates the diamond's light performance with the help of a proprietary algorithm developed by us through extensive scientific research.

Each stone is evaluated in six categories:

  • visual inspection
  • microscopic examination
  • optical index calculation
  • market availability
  • ring design comparability
  • comparative pricing

The formula can be used to calculate the cut index of any modern round brilliant accompanied by a GIA certificate. The index is measured on a scale of 0 to 100, with 100 being the highest possible score. In practice, the highest score never exceeds 97. Margins of less than 10 points are irrelevant and should be ignored.

We do not recommend choosing a diamond based solely on the index. Each stone has its own character and beauty. A diamond with a lower index might seem more attractive to some people.

We do not recommend choosing a diamond based solely on the index. Each stone has its own character and beauty. A diamond with a lower index might seem more attractive to some people. The Diamond Cut Evaluation Index comes in handy when you need to break a tie between otherwise identical ideal-cut round diamonds.


The calculation is based on the stone's table and height percentage, as well as crown and pavilion angles measured by the GIA and printed on the certificate.

Only GIA-graded stones are eligible for the evaluation. Grades and measurements by gem labs other than the GIA are inconsistent and unreliable. We strongly advise buying GIA-certified diamonds only.

The great majority of round brilliants score way below 50. Only a small fraction of all-round diamonds receive "excellent" -cut, -polish, and -symmetry grades from the GIA. These XXX diamonds score above 50.

A tiny percentage of XXX diamonds with a score of 75 or more are called "super-ideal". It is not an official term, but rather a part of the trade jargon.

Requesting the index

Anyone can request the evaluation. This service is free for consumers. However, we reserve the right to impose a daily limit for heavy users.

Affiliated retailers enjoy free access to the data as well. To find out whether you are an affiliated retailer please ask yourself this question: "When was the last time we ordered from Leon Mege?"

To discourage multiple requests for evaluations without an intent to buy, we may require a retainer. A retainer is required for calculating the index one stone at a time.

To find out the score, simply submit a list of up to five certificate numbers under consideration. In most cases, we can return the results in just a few hours.

The index is not a reflection of the stone's beauty. A human eye cannot distinguish between two diamonds with a close score.

The index is designed to highlight the minute differences in the cut. In combination with the slight price differences, it can help to spot the most attractive stone.

The index is a simple way to break a tie between several nearly identical stones without the need to become a gemologist. It will save your time trying to make sense of contradicting and often misleading information found online, just to pick one diamond.

We will work with you directly and supply the best-looking and best-priced diamond on the market. After all, we guarantee to match or beat the lowest diamond price.

When we hand-pick diamonds for you, we do not rely on the index; we go much deeper. We inspect potential diamonds using our exclusive 23-point evaluation system.

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