Diamond Table Percentage Explained for Lab-Grown Diamonds
A clear guide to diamond table percentage, how it affects appearance, and why balanced proportions matter when selecting a lab-grown diamond.
Last updated: May 2026
Diamond table percentage measures the width of a diamond’s top flat surface compared to the diamond’s overall width. It is one of the key proportion measurements shown on grading reports and plays an important role in overall appearance.
Quick answer: A balanced table percentage can help support brightness, fire, and overall visual balance, while extremely large or small tables may reduce a diamond’s visual performance. Table percentage should always be evaluated together with cut quality and overall proportions.
Although table percentage is important, no single number determines whether a diamond is beautiful. The best lab-grown diamonds combine balanced proportions, strong cut quality, and attractive overall appearance.
What Is Diamond Table Percentage?
The table is the large flat facet located on the top of a diamond. Table percentage compares the width of that facet to the diamond’s overall width.
The formula is:
Table Width ÷ Diamond Width × 100 = Table Percentage
For example, if a round diamond has a table measuring 3.75 mm and an overall width of 6.50 mm, the table percentage would be approximately 57.7%.
This percentage appears on grading reports from organizations such as IGI and GIA.
Why Table Percentage Matters
Table percentage affects how light travels through the diamond and how the diamond visually balances brightness, fire, and contrast.
Very large tables may increase white brightness but can sometimes reduce fire and make the diamond appear flatter or less balanced.
Very small tables may increase fire in some cases, but they can also reduce overall brightness or create less balanced light return if the rest of the proportions are not well matched.
Balanced proportions generally perform better than diamonds optimized around one isolated measurement.
Preferred Table Percentage for Round Diamonds
For round lab-grown diamonds, many well-performing stones fall within a moderate table range rather than at extreme measurements.
- Often preferred: approximately 54%–58%
- Potentially too small: below roughly 53%
- Potentially too large: above roughly 60%
These ranges are general guidelines rather than strict rules. Table percentage should always be reviewed together with crown angle, pavilion angle, depth percentage, symmetry, and overall cut quality.
Table Percentage vs Depth Percentage
Table percentage and depth percentage work together to influence appearance.
A diamond with a favorable table percentage can still perform poorly if the depth percentage or other proportions are unbalanced.
For this reason, buyers should avoid filtering diamonds based on table percentage alone.
Can Table Percentage Affect Sparkle?
Yes. Table percentage influences how light reflects and disperses inside the diamond.
Balanced tables can help support a mix of brightness and colorful fire, while extreme table sizes may reduce visual balance.
However, sparkle is influenced by the entire cut structure of the diamond, not just the table percentage by itself.
Do Fancy Shapes Use Different Table Ranges?
Yes. Fancy-shaped diamonds such as oval, emerald, cushion, pear, and radiant cuts often use different table percentage ranges than round diamonds.
Because fancy shapes vary significantly in faceting style and outline, there is no single ideal table percentage that applies universally across all shapes.
Fancy shapes should be evaluated based on overall visual balance, light performance, outline quality, and the presence of issues such as dark areas or bow-tie effects.
Should Buyers Focus Heavily on Table Percentage?
Table percentage is useful, but it should not become the primary buying decision by itself.
A strong buying process usually starts with overall cut quality, then reviews table percentage together with color, clarity, certification, proportions, and visual appearance.
Well-balanced diamonds typically perform better than diamonds selected around one isolated number.
Final Thoughts
Diamond table percentage helps explain how a lab-grown diamond was proportioned during cutting. Balanced table sizes can support brightness, fire, and overall visual harmony, while extreme tables may reduce performance.
For most buyers, table percentage should be treated as one important detail within the broader evaluation of cut quality and overall appearance.