Hong Kong’s First Trusted Lab-Grown Diamond Scoring Calculator
MadisonDia Ideal Sparkle Index™
Enter your diamond’s proportions to evaluate its brilliance and fire. Use together with your official IGI certificate.
MISI™ Ideal Sparkle Index Score
RecommendedRecommended: Exceptional brilliance and fire.
How to read this: the score combines cut, proportions, polish, symmetry, and girdle quality. Fire leakage is light lost through proportion deviation — the higher the score and the lower the leakage, the better the sparkle. Always refer to your IGI certificate.
This evaluation is for reference only and not an official certification. MadisonDia is not a grading authority. Always cross-check with your IGI certificate.
MadisonDia Ideal Sparkle Index™ MISI – Diamond Calculator (Brilliance & Sparkle Score Tool)
What Is the MadisonDia Ideal Sparkle Index™ (MISI™) Diamond Calculator?
The MadisonDia Ideal Sparkle Index™ (MISI™) is a free diamond sparkle calculator that scores a lab-grown diamond's brilliance, fire, and overall sparkle on a simple 0–100 scale.
Most diamond reports are full of numbers that only a gemologist can read. MISI™ takes that complex cut data and turns it into one easy score, so you can tell at a glance how lively a diamond will actually look on your hand. To keep the score honest, we use a non-linear system: small differences in cut quality create clear gaps in the score, which makes it easy to separate a truly exceptional stone from a merely "good enough" one.
The three things sparkle is made of
MISI™ Sparkle Score Chart: What Each Lab-Grown Diamond Rating Means
Use this chart to read any MISI™ result in seconds. Every diamond MadisonDia sells scores 80 or above, so you start from a high-quality floor.
| Score | What it means for you |
|---|---|
| 93–100 | Exceptional — maximum sparkle and fire. The top tier for buyers who want the very best light performance. |
| 85–92 | Excellent — outstanding sparkle that looks visually comparable to top-tier diamonds in everyday wear. |
| 70–84 | Good — stable, reliable brilliance and strong value for budget-conscious buyers. |
| 55–69 | Average — some compromise in light return. Worth a closer look before you commit. |
| Below 55 | Poor — limited brilliance. Not recommended. |
How Your Lab-Grown Diamond Sparkle Score Is Calculated
The MISI™ score is built from the two things that decide how a diamond handles light — its proportions and its finish. When these are right, light enters the top, bounces around inside, and returns to your eye as sparkle. When they're off, light leaks out the bottom and the stone looks dull.
- Proportions — table size, total depth, crown angle, and pavilion angle. Ideal proportions return the most light.
- Cut quality — polish and symmetry, which control how cleanly each facet reflects.
- Girdle thickness — too thick or too thin can quietly reduce sparkle and durability.
- Fire leakage — light escaping through the bottom instead of returning to your eye is penalised, because it directly lowers what you see.
Because the penalties are non-linear, a diamond that is slightly outside the ideal range loses more points than you might expect — which is exactly how a real eye perceives the difference in person.
Why the MISI™ Sparkle Score Matters When You Buy a Diamond
Two lab-grown diamonds can share the same carat, colour, and clarity grade and still sparkle very differently — and that difference comes down to cut. The MISI™ score makes that hidden gap visible, so you can compare stones fairly instead of guessing from a spec sheet. For a deeper dive on choosing a stone, see our lab-grown diamond engagement ring buying guide, or browse our round lab-grown diamonds to see MISI™ in action.
MISI™ Score vs IGI & GIA Diamond Certification — What's the Difference?
This is an important distinction, so we keep it crystal clear: MISI™ is a supplementary sparkle tool, not a grading certificate. The official grade of every MadisonDia diamond comes from an independent third-party laboratory — never from us.
You can verify any certificate directly with the issuing lab: check an IGI report at the IGI Report Verification service, or a GIA report at GIA Report Check. To understand what each line on a certificate means, read our lab-grown diamond certification guide.