What is Diamond Polish?

Polish refers to the smoothness and quality of a diamond's facet surfaces after cutting and polishing. It measures surface-level defects visible under 10x magnification.

GIA polish grades (from best to worst):

  • Excellent: No visible polish marks under 10x magnification
  • Very Good: Minor polish marks visible only under 10x magnification
  • Good: Noticeable polish marks under 10x magnification, rarely visible without magnification
  • Fair: Obvious polish marks under 10x magnification, may be barely visible to naked eye
  • Poor: Prominent polish marks visible even to naked eye

Polish affects how light interacts with facet surfaces. Poor polish can create hazy appearance or reduce sparkle.

What is Diamond Symmetry?

Symmetry measures how precisely facets are aligned and shaped. It evaluates uniformity of facet size, shape, and placement.

GIA symmetry grades (from best to worst):

  • Excellent: Facets precisely aligned, meeting points exact, no asymmetry under 10x magnification
  • Very Good: Minor asymmetry visible only under 10x magnification
  • Good: Noticeable asymmetry under 10x magnification, rarely affecting appearance
  • Fair: Obvious asymmetry under 10x magnification, may slightly affect light performance
  • Poor: Significant asymmetry affecting light performance and appearance

Symmetry affects light path through the diamond. Poor symmetry can create dead zones or reduce brilliance.

Do Polish and Symmetry Affect Beauty?

The Practical Reality

For most diamonds, polish and symmetry grades above "Good" have minimal visual impact on beauty to the naked eye.

When Polish Matters

Polish becomes noticeable:

  • In high-clarity diamonds (VVS and above) where surface is highly visible
  • In step-cut shapes (emerald, Asscher) where large facets show surface quality
  • When polish is "Fair" or "Poor" (creates visible haze)

When Symmetry Matters

Symmetry becomes noticeable:

  • In larger diamonds (2+ carats) where facet patterns are more visible
  • When combined with marginal cut quality
  • When symmetry is "Fair" or "Poor" (creates visible off-center patterns or dead zones)

The Bottom Line

Excellent vs. Very Good polish/symmetry: Rarely visible difference to naked eye

Very Good vs. Good polish/symmetry: Often indistinguishable without magnification

Good vs. Fair: May show subtle differences in certain diamonds

Fair vs. Poor: Usually visible degradation in appearance

Recommended Polish and Symmetry Grades

For Round Brilliant Diamonds

Minimum acceptable: Very Good polish and symmetry

Ideal: Excellent polish and symmetry (if price premium is minimal)

Budget option: Good polish with Very Good symmetry (acceptable for brilliant cuts)

For Fancy Shapes

Emerald and Asscher cuts: Minimum Very Good polish and symmetry (step cuts show finish details)

Other fancy shapes: Very Good or better recommended

By Diamond Size

Under 1 carat: Very Good polish/symmetry acceptable

1-2 carats: Very Good to Excellent polish/symmetry

Over 2 carats: Excellent polish/symmetry preferred

By Clarity Grade

SI1-SI2: Good polish/symmetry acceptable (inclusions are bigger concern)

VS1-VS2: Very Good polish/symmetry recommended

VVS1-IF: Excellent polish/symmetry to match high clarity

Polish and Symmetry Impact on Price

Diamonds with Excellent polish and symmetry command 5-15% premiums over Very Good grades, despite minimal visual difference.

Price Premium Analysis

Example: 1.0 carat, G color, VS2, Excellent cut

  • Excellent/Excellent polish/symmetry: $7,000
  • Very Good/Very Good polish/symmetry: $6,300 (10% savings)
  • Good/Very Good polish/symmetry: $6,000 (14% savings)

Value Strategy

Unless you're buying VVS+ clarity or 2+ carats, the price premium for Excellent vs. Very Good polish/symmetry rarely justifies the cost. Very Good grades offer excellent value without meaningful visual compromise.

Triple Excellent (Triple Ex) Diamonds

"Triple Excellent" or "Triple Ex" refers to diamonds with Excellent grades for cut, polish, and symmetry. These diamonds command premium prices.

Are Triple Ex Diamonds Worth It?

For most buyers: No. The difference between Excellent and Very Good polish/symmetry is usually invisible to the naked eye.

When Triple Ex Makes Sense

  • High-clarity diamonds (VVS1-IF) where finish is highly visible
  • Larger diamonds (2+ carats) where details matter more
  • Investment pieces or heirloom purchases
  • When price premium is minimal (under 5%)

Better Value Alternative

Excellent cut with Very Good polish and symmetry delivers 95% of the beauty at 85-90% of the price. For most buyers, this is the optimal value combination.

Polish and Symmetry Buying Strategy

  1. Prioritize cut grade first: Excellent cut matters far more than Excellent polish/symmetry
  2. Set minimum thresholds: Very Good polish/symmetry for brilliant cuts, Excellent for step cuts
  3. Evaluate price premium: If Excellent costs under 5% more, consider it; if 10%+ more, skip it
  4. Match to clarity: Higher clarity deserves better polish; SI diamonds don't need Excellent
  5. Consider shape: Emerald and Asscher cuts benefit more from Excellent finish than brilliant cuts
  6. Use savings strategically: Put savings from Good/Very Good finish toward better cut or color

Polish and Symmetry: Final Recommendations

  • Very Good is excellent value: Minimal difference from Excellent for 10% less
  • Avoid Fair and Poor: These grades can affect visible appearance
  • Don't obsess over Triple Ex: Usually expensive and rarely visually different
  • Prioritize cut quality: Cut grade matters far more than polish/symmetry
  • Match to diamond specifics: High clarity and step cuts deserve better finish
  • Compare side-by-side: If possible, view Excellent vs. Very Good to see minimal difference

Polish and symmetry are tertiary factors after cut, color, and clarity. Very Good grades offer outstanding value for most diamonds. Reserve Excellent finish for high-clarity, large, or step-cut diamonds where details matter most.