When a diamond crystal comes from the ground, the brilliance, fire, and scintillation that constitute the unique beauty of a polished diamond are still locked within it. The way in which a diamond cutter decides to the cut the diamond ultimately determines the diamonds beauty and brilliance.
The pavilion angle is the angle of the pavilion facets in relationship to the girdle plane.
Today most cutters and gemological experts agree that varying more than one degree from a pavilion angle of 40.75 degrees on a Round Brilliant Cut Diamond reduces a diamond's optical efficiency, and thus its beauty.
The pavilion angle is a very important element of a diamonds proportions and it is greatly responsible for the amount of brilliance that a diamond will display.
The pavilion angle for a round brilliant cut diamonds will be different than it is for fancy shaped diamonds. To learn more about the proper pavilion depth percentage for fancy cut diamonds, call or visit Droste's and speak to one of our Certified Gemologist-Appraisers.
Diamonds which have ideal to very fine cut with proper pavilion angles provide the greatest brilliance. The facets on the bottom of a diamond are called pavilion facets.
When you look at a round brilliant cut diamond face-up, the pavilion facets act as mirrors which reflect the image of the table, the large facet on the top of the diamond. This white table reflection seen within the center of the diamond provides the sparkle in the center of the diamond.
In a Very Fine to Ideal cut Round Brilliant Cut Diamond the diamond will exhibit a white table reflection that appears in the center of the table. This reflection should be 1/4 to 1/2 the size of the large table facet on top of the diamond
The AGS Ideal 0 Cut grade includes a narrow range of pavilion angles from 40.5 degrees to 41 degrees.
Ideal to Very Fine Cut Diamonds round Brilliant Cut Diamonds have pavilion angles between 39.7 Degrees and 41.7 Degrees. Diamonds within this range usually provide excellent brilliance. Diamonds that have depths outside these ranges usually cost less, but a degree of brilliance is lost. The diagram below illustrates how the white table reflection changes in size as the depth percentage changes.
The white table reflection appears larger as the pavilion angle increases and smaller as pavilion angle decreases.
- 37.0 = Girdle seen in table
- 38.0 = reflection broken up
- 38.5 = reflection broken up
- 39.0 = 1/8 size of table
- 39.7 = 1/4 size of table
- 40.5 = 1/3 size of table
- 40 = 1/3 size of table
- 41.7 = 1/2 size of table
- 42.0 = 5/8 size of table
- 42.5 = 7/8 size if table
- 43.0 = Dark table facets
- 44.0 = Dark star facets
Increasing the pavilion angle causes light to leak out the pavilion and makes the center of the stone noticeably darker.
In diamonds with very deep pavilions, the darkness covers the entire table and extends out into the star facets, creating what many experts call a nail head. On the other hand, decreasing the pavilion angle by just two degrees often produces a fisheye with a gray girdle reflection visible through the table.