Radiant Cut Depth Percentage:

Specific proportions regarding the ideal depth of a radiant cut diamond have not been conclusively determined or published by Gemological Institute of America. Ideal proportion is more difficult to establish in a radiant cut diamond than in a round diamond. A round diamond has a consistent pavilion angle that makes ideal proportions easier to establish as a depth percentage. A radiant cut diamond has a pavilion that is made up of a variety of angles due to a unique pavilion shape and variance in length and width. (See Diagram)

The depth percentage of a radiant cut diamond is determined by dividing the depth measurement by the diameter measurement. The diameter is determined by measuring a radiant cut diamond's width from side to side. The longer length measurement is not taken into consideration when calculating diameter. By viewing a radiant cut diamond from the end view you can see how slightly different the pavilion looks from that of a round diamond. Radiant cut diamonds require a diamond cutter to cut a steeper pavilion angle than what is normally cut on a round diamond. This steeper angle ensures greater brilliance in a radiant cut.

A radiant cut diamond has a uniquely beautiful shape that is favored by many women for its beauty as well as its unique design capabilities. It is the only truly rectangular diamond shape that has striking brilliance superior to the emerald cut. The diagram illustrates a variety of radiant cuts showing changes in appearance due to differing depth percentages and length-to- width ratios. The proper depth percentage for a radiant cut is between 65% and 80%. You will find that a radiant cut diamond cut within this range will deliver more brilliance. A radiant cut diamond that is cut shallower than 65% will let a greater percentage of light leak through the pavilion which results in less diamond brilliance. Radiant cut diamonds with depth percentages greater than 80% will appear darker in the center due to a large amount of light refracting through and out the bottom of the diamond.

Radiant cut diamonds that are closer to square in measurement will be more brilliant if the depth percentage is within the range of 65% to 75%. Radiant cut diamonds that have more rectangular shapes exhibit greater brilliance with depth percentages between 70% to 80%. When choosing a radiant cut diamond be aware of the depth percentage and length-to-width ratio; they will give you better indication of the the brilliance that a radiant cut exhibits. Gemologist-Appraisers will be happy to help guide you to the most brilliant radiant cut diamond your money can buy.

View Section Diagram of Radiant Shape Length-to-Width Ratios: