Gem & Diamond FAQ

What is an ideal cut?

An ideal cut describes a round brilliant that has been cut to exact mathematical proportions. Each one of the 58 facets are placed at optimal angles to create an ideal balance between light reflection and refraction. There is more that one definition for Ideal Cut, for example: Tolkowsky Ideal, European Ideal, and AGS Ideal. From these, AGS has the best reputation because of their strict proportions.

How does Light Reflection and Refraction affect the beauty of a diamond?

When light enters an Ideal cut Diamond, it is reflected from facet to facet and then is released from the crown only, therefore creating maximum brilliance. If the stone is cut too deep in order to retain weight, light entering the stone will leak out the bottom and so the brilliance is lost. On the other hand, if the stone is too shallow, light will also leak out and the stone will appear glassy, this is also referred to as the fish eye effect.

What are the proportions for AGS ideal cuts?

As AGS Ideal Cut will have the measurements within the following ranges.

  • Total depth percentages between 58-63.5% Table percentages must be between 52.4-57.5%
  • Crown Angles must be between 34-35.5 degrees.
  • Pavilion depth percentage must be between 42.5-43.5%
  • Girdle must be thin to slightly thick

Which proportions produce an attractive Diamond?

Even though there are many ways to cut an attractive diamond, there is a general range of measurement that often work well.

  • Total depth percentage can range from 57-63%
  • Table percentages can range from 55-64%
  • Crown angles can range from 33.5-35.5 degrees.
  • Pavilion depth percentage can range from 42-44%

Remember, beauty is in the eye of the beholder. A round diamond falling into the above ranges is very often a brilliant and attractive diamond.