A diamond certificate (grading report) is the single most important document in any online diamond purchase. Without it, you have no independent verification of what you are actually buying. With it, you know exactly what you are getting — down to the hundredth of a carat.
What a Grading Report Tells You
A GIA or IGI diamond grading report includes:
- Carat weight: Exact weight to the hundredth (e.g., 1.02ct)
- Color grade: D through Z scale
- Clarity grade: FL through I3 scale
- Cut grade: Excellent, Very Good, Good, Fair, Poor (GIA rounds only)
- Measurements: Exact dimensions in millimeters
- Depth %: How deep the diamond is relative to its width
- Table %: How large the flat top facet is relative to the width
- Symmetry: How precisely the facets align
- Polish: How smooth the surface finish is
- Fluorescence: Whether the diamond glows under UV light
- Clarity plot: A diagram showing the location and type of inclusions
- Inscription: Laser-inscribed report number on the diamond's girdle (verifiable under magnification)
Trusted Labs vs. Unreliable Labs
| Lab |
Trust Level |
Notes |
| GIA |
Highest |
The gold standard. Strictest, most consistent grading. Non-profit. Universally accepted for natural diamonds. |
| IGI |
High |
Industry standard for lab-grown diamonds. Reliable and consistent. Also grades naturals. |
| AGS |
High |
American Gem Society. Excellent cut grading system. Less common but very reliable. |
| EGL |
Low |
Grades 1–3 levels more generously than GIA. An EGL "G" color might be GIA "I" or "J". Avoid. |
| GSI |
Low |
Used by some big-box retailers. Less strict grading. Grades may be inflated. |
| In-house / store grading |
Avoid |
Not independent. The seller is grading their own product. Conflict of interest. |
Critical warning: Some retailers sell EGL-certified diamonds at prices that suggest GIA-equivalent grades. An EGL "G/VS2" diamond priced like a GIA "G/VS2" is a ripoff — the actual quality is closer to GIA "I/SI1". Always check which lab issued the certificate.
How to Verify a Certificate
- Find the report number on the diamond listing (usually displayed prominently)
- Go to the grading lab's website:
- Enter the report number
- Compare every spec — carat weight, color, clarity, measurements — to what the retailer listed
- If anything does not match, or the report number is not found, do not buy that diamond
Laser inscription: Most GIA and IGI diamonds have the report number laser-inscribed on the girdle (the edge of the diamond). This microscopic inscription is verifiable by any jeweler with a loupe or microscope, confirming the diamond matches its certificate.
For a deeper dive into how certification works, read our Diamond Certification Guide.
Every Diamond We Sell Is Certified
GIA and IGI grading reports included with every diamond. Verify before you buy.
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