How to buy an Ideal Cut Diamond

What does Ideal Cut mean?

Ideal Cut is a term coined by diamond connoisseurs to mean a Round Diamond cut to proportions originally established in the 1919 doctoral dissertation of diamond cutter Marcel Tolkowsky.

Tolkowsky, using a two-dimensional model of a diamond, calculated that the best possible balance of brilliance and dispersion would result from a 53 percent table, 16.2 percent crown height, a 43.1 percent pavilion depth, no culet, and a knife-edge girdle.

Nowadays, the numbers have been expanded to include a table of up to 57.5 and other criteria. These include very precise angles for the crown height and pavilion depth.

Table diameter: 53 to 57.5%
Crown angle: 34 to 35 degrees
Crown height: 15 to 16.2%
Girdle thickness: thin to medium
Pavillion angle: 41 degrees
Pavillion depth: 43 to 43.5%
Culet: very small- Pointed
Total depth: 60 to about 63%
But the AGS 0 grade doesn't just address a diamond's proportions: it also means the diamond has excellent symmetry and polish

How do you measure a diamond for Ideal cut measurements?

The diamond is measured with a laser measuring machine manufactured by Sarin, OGI, Megascope and others. They will measure the 58 facets of the diamond and assign a grade to each of the different angles. The grade assigned will be the lowest of all of the grades, meaning that if one of the grades is lower, the lower grade will be assigned.

The highest grade is 0. If the diamond achieves a 0 on each of the depth, table and angles it will receive a 0 overall grade.

These machines cannot measure polish.

This is then printed out either on a chart or on a label, depending on the machine.

Certification:

AGS

The AGS Laboratories which is the gemological branch of the prestigious American Gem Society grades diamonds for cut and assigns grades for these parameters and also for Polish and Light Performance. The grades run from Ideal, Excellent, Very Good, Good down to Fair.

GIA

The GIA on the other hand, spent a lot of money and research, running computer simulations of over 38.5 million proportion combinations and tens of thousands of visual observations and came to the conclusion that there is no one set of parameters that can be called Ideal. Many different combinations also produce beautiful diamonds.

 As the GIA explains, there are different regional preferences for diamonds and one size does not fit all.

To quote Bill Boyajian President of the GIA writing in the GIA publication “The Loupe” of Winter 2006:

 “ Diamonds after all are an extraordinary gift of nature. Our attraction to them comes from the mystique and beauty that surrounds every crystal cut. And once cut, the inner brightness and fire that make every diamond unique-and a great reassure of humankind-can be seen in its individual glory”.

 The GIA started to issue cut grades on their reports beginning January 1, 2006.

Should I buy Ideal Cut?

This is up your individual preference. As the GIA writes, many differently cut diamonds are also inherently beautiful. You really should not become hung up on numbers that in real life do not have much bearing on the beauty of the diamond.

If my Diamond is not Ideal, does it mean that I have an inferior diamond?

Absolutely not. The proof; A D Internally Flawless even in a bad make is worth more than a lower color and quality diamond of Ideal Cut.

I do want an Ideal Cut Diamond. How can I ascertain that the diamond I buy is truly Ideal Cut?

Buy an AGS certified diamond with Ideal Ideal Proportions . Another option is the old GIA certificates showing Excellent Excellent and the diamond having a Sarin report of 000.

The reason that you cannot use the new GIA reports is that the GIA does not consider the proportions used by the AGS as Ideal.

What does Hearts and Arrows mean?

In the 1980’s, a viewer came into use in Japan, which showed that a diamond cut to Ideal proportions and being very symmetrical, would show an arrow pattern when viewed from the top, and a hearts pattern when viewed from the bottom of the diamond.

If the diamond is out of round and not symmetrical, this pattern will not show. This is a good way of ascertaining that the diamond is beautifully cut and will mirror the light all. This will give a 98% reflection of light resulting in a diamond with high fire and brilliance.
 

Laser Inscription;

Technology has given the ability to etch the number of the diamond and any other information you want on the girdle of the diamond. This is very hard to see even under 10x magnification.

Most laboratories will laser inscribe the certificate number on the diamond if so requested and will note it on the certificate. Most manufacturers at the moment refrain from inscribing the number, so that they still have the opportunity to recut the diamond to higher qualities.

There are companies that can laser inscribe the number and even a message on the diamond at low cost. Obviously, it won’t be noted on the certificate until it is resubmitted to the lab.

In conclusion; buy a diamond with a report from a reputable lab. Enjoy it and bask in the beauty that it shows and represents.

Now what are my credentials to write about this topic? I am the diamond maven of eBay selling Diamonds in my store and on my website. The Diamond Maven. My eBay username is aurely.

I am a member of eBay since 1998 with gratified customers throughout the eBay world. In real life, I’ve been a Diamond Dealer and Manufacturer since 1978 and have a solid knowledge of diamonds picked up in my over a quarter of a century in the trade.

I enjoy buying Ideal Cut diamonds and am a serious buyer of AGS Certified Ideal Cut Diamonds.

I actually buy the diamonds and put my money where my mouth is. If I’m selling a SI2, you can be assured that it won’t have a black pique staring you in the eye! It’s going to be pleasant. Many Internet sellers don’t see the diamond they are selling and will sell you the diamond on which they make the most money.