Fundamental principles of optical science determine that a diamond's geometry is solely responsible for its desirable "brilliance and fire". Unlike the mutually contradictory "cut grade" schemes of the leading gem laboratories, our e-Praise Cut Score (eCS) numerically rates the cut quality of a diamond in strictly geometrical terms. Considering anything else in assigning a "cut grade" only serves to muddy the issue. eCS does not consider details such as symmetry, finish or polish. All of these other features are not ignored, however. They all still contribute in their own right to the value of a diamond as determined by a professional appraiser. All of the other features being equal, a diamond with eCS=1.000 is cut with the right geometry to elicit the maximum brilliance from the rough diamond material from which it is made.

The influence of the diamond's eCS score on its monetary value, as used in our e-Praisal formula, may fairly be visualized as adjusting the value to that of the largest ideally cut diamond that is entirely contained within the subject diamond. For the sake of maximizing the stone's brilliance, rather than its weight, that is the gem that the cutter should have created from the rough diamond. A diamond with eCS=1.000 has measurements in the narrow range of ideally cut diamonds of the same weight. It lives up to its label.

eCS is not proprietary to a single laboratory. It uses only objectively measured scalar values that are sure to be accurately reported in any major lab certificate. For this reason, a diamond's certified data will yield the same eCS number regardless of the brand of its certificate. It is therefore the only unbiased common basis for comparing diamonds. By its nature, eCS single-mindedly addresses actual "brilliance and fire", without attempting to influence competitive prices. It removes an unnecessary opportunity for chicanery and confusion from the retail diamond trade.

eCS=1.000 vs. "Ideal" Cut Grades:

We were particularly interested in seeing how an eCS=1.000 score compares in practice with the top "cut grades" assigned by the major laboratories. We took the data from 128 certificates (q.v.) arbitrarily representing the three top labs. Each certificate assigns its diamond to the top cut grade given by that laboratory, as follows:

Of these 128 examples of "ideal" stones chosen from the listings of leading retailers, only 9 (7%) of them are eCS=1.000. The others have as much as a 10% deviation from the objectively ideal range of proportions identified by eCS=1.000.

You may wonder why 93% of these diamonds could be given "ideal" cut grades, but not score eCS=1.000. Sadly, the gemological laboratories have chosen lately to compromise their reputations by devising their own convoluted "cut grade" systems to court certification business from retailers. By obfuscating the issue, they can be deceptively lenient in giving more diamonds a top rating. This puffs more stones to help the retailers. Before they began doing this, they were content to stick to their proper and traditional role in the diamond industry, namely to serve as honest, disinterested reference laboratories. Their certificates should record only strictly determined, objective physical features. Laboratory certificates are not appraisals, and therefore should not also attempt to report any indication of overall monetary value. That is the purview of the professional appraiser.

We would go so far as to advise buyers to consider eCS=1.000 to mean "correctly cut" and any other eCS score to indicate "incorrectly cut".

eCS=1.000 vs. "Hearts and Arrows":

In a separate survey of 30 listings (q.v.) of so-called "Hearts and Arrows" diamonds, we found that these heavily promoted stones consistently scored eCS's of about 0.970 (0.967 ± 0.018, 1 s.d., n=30). This narrow cluster of values, and the fact that not one scored eCS=1.000, suggests two possibilities to explain their creation: Either they were deliberately cut 3% away from "ideal" for the purpose of showing the arbitrary H&A reflections, or they were identified by their reflection patterns from among the many stones that are inadvertently cut off target for proportions. Thus they either create or salvage a class of relatively inferior diamonds to command "Ideal Cut" prices through the clever marketing of a gimmick. In our opinion, the title "Hearts and Arrows" might be interpreted to mean "cutely but improperly cut".

Our "insider's advice" for obtaining the best diamond value:

Consider purchasing only eCS=1.000 stones. From among those, then choose Color H (G if to go with yellow gold) and Clarity VS₂. This will save you a medium size fortune (about 60% savings over a Color D, Clarity F stone) on a gorgeous diamond. All the gradations of Color and Clarity above those are "differences that don't make a difference". Avoid marketing gimmicks.

An important note: The "cut grades" from the labs are assigned only to Round Brilliant and Square Princess stones. eCS applies to a wide variety of modern shapes and cutting styles.