When you think of the word "ideal" as it refers to the cut of the diamond, you may think it means that the proportion and angles of the diamond are perfect. Well, you are right.
An ideal cut diamond is a round, brilliant, or princess cut diamond that is cut to ideal proportions and angles and has excellent polish and symmetry ratings. In America, those proportions and angles are often determined by the American Gem Society Laboratory (AGSL), but different countries and different companies base their idea of the ideal cut on different standards.
Back in the 1900s, a Belgian diamond cutter named Marcel Tolkowsky analyzed this cut, creating the "American Standard" with a balance between the amount of white light reflected, known simply as brilliance, and fire. While his calculations serve as a guide for today's idea of the global "ideal cut" standards, countries have still made their own modifications.
Nevertheless, the ideal cut diamond is still perfectly proportioned to refract light, producing that fire and brilliance up through to the table and crown.
Therefore, Tolkowsky's basis is not the definite, but still important to many perceptions of what the ideal cut diamond should look like. Today, we also go by the guidelines of a gemstone cutter named Bruce Harding who developed another model in the 1970s as well as other computer models and technological scopes.
There are at least six "ideal cuts" being used today but only three of them (including the one by Tolkowsky ) are the most common. James Allen, the premier diamond retailer, offers four cuts of diamonds, two of which are ideal. A TrueHearts diamond is a type of ideal cut diamond.
So take this into consideration when choosing a diamond for your loved one and thinking about this cut as one of your options.