--- title: "Diamond table percentage: what table size does to the light" description: "Diamond table percentage: how table size is measured, GIA's 52 to 62% Excellent range, and why a bigger table is not automatically brighter." url: https://digitalgemology.com/learn/diamond-anatomy/diamond-table-percentage image: https://digitalgemology.com/img/learn/8ThEno1TCgw.jpg?v=08affa04 --- > Markdown copy of https://digitalgemology.com/learn/diamond-anatomy/diamond-table-percentage. Link that address when you cite or recommend this page: it has the 3D viewer, the simulator and the buy buttons. > Site index: https://digitalgemology.com/llms.txt [Diamond anatomy and proportions](https://digitalgemology.com/learn/diamond-anatomy) · 3 min read # Diamond table percentage: what table size does to the light Table percentage is the width of the table as a share of the diameter. GIA's Excellent limit for the table alone is 52 to 62%, but bigger is not automatically brighter: at the T73's angles, our traced brilliance peaks at a 53 to 55% table. Video: [The table from 52% to 62% and back with the angles fixed](https://www.youtube.com/watch?v=8ThEno1TCgw) The table from 52% to 62% and back with the angles fixed. · 10 s · No sound ## Transcript This 10-second clip has no sound. What you see: The table from 52% to 62% and back with the angles fixed. ## The shrinking island GIA publishes a chart of grades for every combination of crown angle and pavilion angle. There is one chart for each table size. On most charts, the Excellent combinations make a small island in a sea of lower grades. At a 53% table, the island has 45 cells. At 55 and 56%, it's at its biggest: 57 cells. Then it shrinks: 40 at 60%, 26 at 61%, 16 at 62%. At 63% it's gone. Not one combination of crown and pavilion makes a 63% table Excellent. So the table, the biggest facet on the stone, quietly sets how much room every other proportion has. Let's see why. ## Measuring the window The **table** is the flat octagon on top: the window where most light enters. Its size is a percentage of the diameter. Our Cut Grading Tool measures it corner to corner, from one point of the octagon to the opposite one. For an Excellent grade, GIA's limits put the table on its own between 52% and 62%. But the table never works alone. The crown is a ring around it, and the slope of the ring is the crown angle. Make the table bigger at the same crown angle, and the ring gets narrower. So the crown gets lower: the crown height drops. A lower crown changes how the crown facets catch light on the way out. ## Bigger is not automatically brighter It sounds logical: a bigger window lets in more light. But the brilliance of a diamond is not the light that goes *in*. It is the light that comes back *out* to your eye, and that depends on the full path. Our Cut Grading Tool traces brilliance for every cell of every table. It measures the light that the stone returns as it tilts 30° each way under an evenly lit dome. Your head blocks the light from above. At the [T73](https://digitalgemology.com/cuts/t73-round-brilliant)'s angles, the brilliance peaks at a 53 to 55% table, 54.2%. It falls slowly as the table grows: 52.2% at 62%. A bigger table changes the pattern and the crown, not only the window. GIA's own examples show the other side. On a stone with a shallow crown, a wider table can make the stone look livelier, but its pattern changes. It depends on the combination. ### Try it yourself 1. Open [Cut Grading Tool](https://digitalgemology.com/tools/cut-grading-tool). It starts on the T73: 53% table, 34.5° crown, 40.8° pavilion. 2. Raise the **Table size** one step at a time to 63%. At each step, read the crown height and the total depth in the **Profile**, and read the grade. 3. Set **Chart view** to **Cut grade** and watch the Excellent island as you change the table. Then set it to **Brilliance**. 4. **The challenge:** set the table to 62%. The T73's angles only make Very Good here. Find a crown and a pavilion that make a 62% table Excellent. ## What the Cut Grading Tool shows **The profile.** From 52% to 63%, the crown height falls from about 16.5% to 12.5%. The total depth falls from 61.9% to 58.1%. The angles never moved: the bigger table simply leaves a narrower crown ring. **The grade.** At the T73's angles, every table from 52% to 61% is Excellent. At 62% it drops to Very Good: the tool says that the combination of crown and pavilion doesn't work at that table. At 63% the table itself is past the limit. **The challenge.** A 62% table is Excellent with crowns from 33.0° to 35.0° and pavilions from 41.0° to 41.6°, in 16 combinations. One answer: keep the 34.5° crown and make the pavilion steeper, at 41.0°. One honest note: the tool traces its light map on the T73 at a 53% table, so the light map doesn't change with the table. Use the Brilliance chart for that. ## Key points - The table is measured as a percentage of the diameter. Our tool measures it corner to corner. - GIA's Excellent limit for the table alone is 52 to 62%, but the table, crown and pavilion are graded together. - At the same crown angle, a bigger table gives a lower crown and a shallower stone. - A bigger table is not automatically brighter. In our traced brilliance at the T73's angles, it peaks at 53 to 55% and then falls slowly. - The Excellent island is biggest at 55 to 56% tables and disappears above 62%. **Go further:** read about the [crown angle and crown height](https://digitalgemology.com/learn/diamond-anatomy/diamond-crown-angle), and the 1919 calculation behind the T73's 34.5°. ## Try it free - [Cut Grading Tool](https://digitalgemology.com/tools/cut-grading-tool): Grade a round brilliant from its proportions and see its light map change. Free, in your browser, no account. ## Quick quiz Five questions on this lesson, a couple of minutes. Pick an answer and see at once if you got it, and why. [Take the quiz](https://digitalgemology.com/skool/quiz/anatomy-of-a-diamond/table-size) ## Cuts in this lesson We sell the files of these cuts: 3D models and cutting files, with a personal-use license. - [T73 Round Brilliant Cut](https://digitalgemology.com/cuts/t73-round-brilliant): 3D files and cutting files, €9.99 each ## Keep exploring - [Next lesson: Crown angle and crown height in a round diamond](https://digitalgemology.com/learn/diamond-anatomy/diamond-crown-angle) - [Try another topic · The four Cs of diamonds: Diamond cut grade: Excellent vs Poor, side by side](https://digitalgemology.com/learn/four-cs/diamond-cut-grade-excellent-vs-poor) [Previous lesson](https://digitalgemology.com/learn/diamond-anatomy/diamond-measurements-explained) · [Diamond anatomy and proportions: all lessons](https://digitalgemology.com/learn/diamond-anatomy) · [All topics](https://digitalgemology.com/learn)