HOW DOES CUT AFFECT THE BRIGHTNESS OF YOUR DIAMOND? IMPORTANT

According to Us, IDEAL CUT DIAMOND Measurements

Marcel Tolkowsky revolutionized the world of round diamonds when he published his groundbreaking book, “Diamond Design” in 1919. In his book, he wrote about a series of proportions that should be applied to a diamond of maximum beauty, sparkle and brilliance, based on mathematical calculations. From this landmark book to the present day, many diamond cutters around the world have widely applied Tolkowsky’s findings when polishing diamonds.

Marcel Tolkowsky's ideal proportions for a round cut diamond

In later modern times, many things changed as Tolkowsky's groundbreaking discoveries were developed further. With the help of special studies and technological advancement, researchers from GIA & AGS published scientific journals that changed the way we polish and purchase diamonds.

One of the greatest innovations was the discovery that ideal cut diamonds did not have to follow a single chain of proportions as Tolkowsky's original thesis suggested. In fact, a diamond could be polished to a different set of proportions and still exhibit the same ideal optics.

General Proportions for Round Cut by Tolkowsky

Table%

52.4% to 57.5%

Depth%

56.88% to 63.92%

Crown Angle

33.7° to 35.8°

Pavilion Angle

40.2° to 41.25°

Girdle Thickness

Thin-Medium

Culet Size

None

Source: Ideal Cut: A Consumer's Guide.

* Note: The historical table above should be used as a reference only. With modern research, the Tolkowsky ratios have been further refined. If you are looking for a diamond that exudes superior brilliance and sparkle, scroll down to use my proven ideal cut diamond ratios table instead.

In his first publication, Tolkowsky stated that the ideal cut diamond should have a surface area ratio of only 53%. However, it is now scientifically proven that an ideal cut can have ratios outside this value and that diamonds with slightly larger surfaces can also achieve ideal optical properties.

Naturally, with all the technical specifications laid out, you might think that if diamond cutters simply followed a standard formula, then all diamonds on the market would have to be polished to ideal proportions. However, this is not the case at all.

In fact, it is estimated that 90% of round cut diamonds are preferentially cut to less than ideal proportions to better suit market interests.

As a consumer, this is what you get when you choose a low-performing round diamond. There should be ABSOLUTELY NO escape when it comes to proportions. When a diamond misses its ideal proportions, its price will change immediately.

Therefore, the prices of two diamonds with the same certificate features will be different from each other.

  • 1.07 F VVS2 EX/EX/EX $3,000 certificate number xxxx434
  • 1.07 F VVS2 EX/EX/EX $3,600 certificate number xxxx818

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The difference comes from the cut-off percentages, that is, from values ​​that you haven't actually examined.

If you want the " most shiny " stone, you have to buy the $3,600 stone. The common misconception here is to think that the $3,000 stone is more affordable or that the seller gave a better price.

I must emphasize here again: If the proportions are not correct, the light performance will be negatively affected (Yes, there may be extreme values, but outside these proportions, the probability of finding a well-cut diamond is extremely low).

Why You Should Avoid Round Cut Diamonds That Don't Have Ideal Proportions

Despite our recommendations, I know there are still some readers and internet trolls or jewelers who will say things like, “Does having something slightly out of the ideal range REALLY affect the light performance that much?”

They will say: "What if the pavilion angle is 0.2°? If this is such a big deal, why did the GIA rate the diamond as triple 'flawless'?"

So, take a look at the following examples of GIA triple ‘flawless’ diamonds. These are proportionally ‘close’ diamonds and I want you to look carefully at how a small variation can greatly affect the light return of a diamond.

We will examine 2 EX/EX/EX GIA reported diamonds…

ASET imagery shows significant light wastage and poor brightness from edge to edge.

The light performance of a diamond is limited by the laws of physics, and this has a direct relationship with the faceted surface proportions. Therefore, if you are considering purchasing a diamond with the most accurate and brightest proportions that do not fit the table I have put above, you should ask yourself the question WHY repeatedly.

It doesn't have to be the BRIGHTEST... There is no problem with this approach either. What we just want to explain here is where the price difference between two different diamonds with the same certificates comes from.