Tolkowsky Ideal Cuts

Starting your online diamond search with focus on ideal cut diamonds is a great path to a brilliant diamond with sparkle and liveliness.  For those looking for absolute perfection, learning about the Tolkowsky Ideal Cut will bring your diamond search to the next level.

Defining Ideal Proportions for Round Diamonds

In 1919, Marcel Tolkowsky (an engineer by education and member of a Belgian family of diamond cutters) wrote a master’s thesis on the ideal proportions for round diamonds. The ideal proportions designated by Tolkowsky were derived from mathematical calculations that considered both the fire and brilliance of the stone.

The target set by Tolkowsky to be considered “ideal” was of a diamond with:

These diamond proportions are considered as well chosen and have been the industry benchmark for diamonds labeled as “ideal” for the past 80 years.  In essence, Tolkowsky can be considered the father of the ideal cut diamond.

Not Everything Ideal is Really Ideal

Marcel Tolkowsky’s ‘ideal proportions’ were intended as a set of general “guidelines” (as certain aspects of a diamond’s cut had not been taken into consideration or explored). Marketing and branding campaigns at times generalize Tolkowsky’s concept of ideal diamond proportions in an effort to label diamonds as “ideal” even though their properties don’t fall within the Tolkowsky’s designated tolerances.  On the other hand, studies have shown diamonds OUTSIDE of the proportions indicated by Tolkowsky can be equally or even more beautiful than a Tolkowsky Ideal Cut Diamond.

When applying your knowledge about Tolkowsky ideal cuts, our recommendation is to use it for filtering out poor performing diamonds and not for final selection.   Find out more in our diamond buying guide.

Using Tolkowsky’s Ideal Proportions

A brilliant diamond is a complex interrelationship of light reflecting and refracting off the many facets of a diamond as light travels through it.  As such, determining which diamonds are desirable and which are overvalued can be tricky.  When starting your diamond search, use Tolkowsky’s ideal proportions as a baseline and a starting tool to help you filter the good from the bad.  Other tools such as Ideal Scope and ASET reports will help you narrow down the best diamond from your set.

Guidelines Proportions for Round Ideal Cut Diamonds:

Total depth between 59 – 61.8%
Table diameter between 53 – 57.5%
Crown angle between 34.3 – 34.9 degrees 
Pavilion angle between 40.6 – 40.9 degrees 
Girdle edge between thin to medium
Culet: none (GIA) or pointed (AGS)

The above guidelines will help you get a stone with the best light performance available.  Some of these parameters need to be entered as part of the “advanced” settings on a online diamond retailers website.  As as example, use our pre-filtered search for ideal diamonds at James Allen.

Leave a Reply

Your email address will not be published. Required fields are marked *

Post comment