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Certified Lab-Grown Diamonds, Delivered with Confidence.

Diamond Cut Guide: Ideal to Poor Explained

Learn how precision proportions and craftsmanship create the brilliance, fire, and sparkle of every certified lab-grown diamond.

Published: November 2025 · Last updated: November 2025

1. What Is Diamond Cut?

Diamond cut is the most critical of the 4 C’s. It determines how a diamond’s proportions, symmetry, and polish interact with light. A perfect cut returns light through the top, producing maximum brilliance and fire.

Cut should not be confused with shape. While shape refers to outline (round, oval, emerald, etc.), cut measures performance — how well the diamond handles light.

2. Cut Grades: Ideal to Poor

  • Ideal — Maximum light return and symmetry; top brilliance and fire.
  • Excellent — Near-ideal performance with outstanding sparkle.
  • Very Good — Minor deviations from ideal; still bright and lively.
  • Good — Some light leakage that softens brightness.
  • Fair — Noticeably less sparkle due to proportions.
  • Poor — Significant light leakage; looks dull.

    Round brilliants are graded by independent labs like IGI and GIA using proportion, symmetry, and polish data.

3. Recommended Proportions for Round Brilliants

  • Table: 54–58%
  • Depth: 60–62.5%
  • Crown Angle: 34–35°
  • Pavilion Angle: 40.6–40.9°
  • Girdle: Thin–Medium
  • Culet: None or Very Small
  • Symmetry & Polish: Excellent

These measurements are for round brilliants — the only shape with standardized cut grades. Fancy shapes (oval, emerald, pear, cushion) don’t have a single “ideal” recipe, so we hand-select top performers by light return, symmetry, and overall beauty.

4. Cut Anatomy

This GIA-style diagram shows true optical behavior. Only an Ideal Cut reflects light back through the top for maximum brilliance and fire; shallow stones leak downward, and deep stones leak sideways.

5. Ideal vs Shallow vs Deep

This GIA-style diagram shows true optical behavior. Only an Ideal Cut reflects light back through the top for maximum brilliance and fire; shallow stones leak downward, and deep stones leak sideways.

6. Cut vs the Other 4 C’s

While the 4 C’s of Lab Diamonds are Cut, Color, Clarity, and Carat, cut has the greatest visual impact. A well-cut H/VS1 diamond often looks brighter than a poorly cut D/IF.

7. Verification & Certification

Each diamond from LabCreated.Diamonds is certified by IGI or GIA and includes a laser inscription matching its grading report for easy verification.

8. Our Promise of Light Performance

  • • IGI or GIA certification with matching laser inscription
  • • VS1 or better clarity, H or better color
  • • Ships within 3–6 business days via FedEx Insured Delivery (adult signature required)
  • • Lifetime Authenticity Guarantee & 12-Month Warranty (excluding wear or abuse)

Each diamond is hand-verified under 20× magnification for symmetry, polish, and proportions before shipment.

Ready to find your certified diamond? Browse our full selection of Loose Lab-Grown Diamonds — each stone is certified and ships within 3–6 business days.

Last updated: November 2025