Diamond Information Depth
The 'Depth' of a diamond is the measurement from the table to the culet. In a round brilliant the Accredited Gem Appraisers (AGA) reccomend a depth between 58.7% and 62.3% of the diamonds diameter for the Perfect Ideal cut.
Marcel Tolkowsky was a pioneer in the world of diamonds, and was the first person to present a mathematical analysis of diamond cut. In 1919 he released the 'Diamond Design' , A study of the reflection and refraction of light in a diamond. He concluded that a diamond , having the most perfect fire and brilliance should have a single set of proportions. A diamond with no culet and an extremely thin girdle should have a 53% table, crown angle 34.5° , crown height 16.2% , pavillion angle 40.75° , pavillion depth 43.1% and an overall total depth of 59.3% . One must remember though that Tolkowsky's set of proportions will be different for any diamond that has a culet or a thicker girdle
