Brilliant Cut Index

brilliant cut index

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

We evaluate the cut grade of any modern round brilliant based on its GIA data. The index is measured on a scale of 0 to 100. Grades within 5 points are nearly identical and do not indicate any advantage over one another. In practice,  the maximum grade rarely exceeds 96-97.

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 and crown and pavilion angles measured by the GIA and printed on the certificate.

The great majority of round brilliants score way below 50. Only a small fraction of 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 a part of the trade jargon.

Anyone can request an evaluation of a stone. It is free for clients, but we limit the number of times the reading is done. To discourage multiple requests for evaluations without an intent to buy, we may require a retainer. 

Affiliated retailers enjoy free access to the data as well. To find out whether you are an affiliated retailer, please call us.

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

Only GIA-graded round brilliants with XXX grades are eligible for the evaluation. Grades and measurements by gem labs other than the GIA are inconsistent and unreliable. Therefore, we strongly advise buying GIA-certified diamonds only.

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 becoming a gemologist. It will save your time trying to make sense of contradicting and often misleading information found online 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. First, we inspect potential diamonds using our exclusive 23-point evaluation system. Then we examine the spreadsheet to spot better-priced stones. Once the work is complete, you get the last say which stone you want.

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    Diamond prices guide