Diamond Cut Grades Compared
Ideal vs Excellent vs Very Good vs Good. Cut is the C that controls sparkle — and the one place in this entire process where cheaping out actually shows. Here's where each grade stops being worth it.
Updated November 2026
Quick verdict
Buy Excellent/Ideal cut. Full stop. Cut determines how much light the stone throws back at you — a poorly cut diamond with flawless color and clarity still looks like a wet ice cube. The price gap between Excellent and Very Good is small; the sparkle gap is visible. This is the one C where you spend up, so you can save on color and clarity, where nobody can see the difference.
The head-to-head
| Grade (GIA scale) | What it means in real life | Price vs Excellent | Buy it? |
|---|---|---|---|
| Excellent / "Ideal" | Maximum light return — the firehose of sparkle Buy this | Baseline | Yes — the default |
| Very Good | Noticeably bright; a trained eye sees slightly less life | ~5–15% less | Acceptable if the specific stone performs on video |
| Good | Visibly duller, often cut deep to preserve carat weight | ~15–30% less | No — you're paying for weight you can't see |
| Fair / Poor | Glassy, dark, or lifeless | Cheap for a reason | Hard no |
Why cut beats the other Cs
Color and clarity are about what the diamond is. Cut is about what the diamond does. Proportions decide whether light entering the stone bounces around and fires back out the top (sparkle) or leaks out the bottom and sides (sadness). A perfectly cut H/SI1 will out-sparkle a badly cut D/VVS1 every single time — at a fraction of the price. Prioritizing cut is the single highest-leverage decision in diamond buying.
"Ideal" vs "Excellent" — marketing or real?
GIA's top grade is Excellent. "Ideal" is the top grade on other labs' scales (AGS historically, now folded into GIA's Ideal designation; IGI also uses Ideal) and a marketing word retailers attach to their best-proportioned stones ("super-ideal," "hearts and arrows," house names like Astor or True Hearts). Super-ideal stones are genuinely the best of the best — precision-cut for textbook light performance — but the premium runs 10–25% for a difference most people can't spot outside a lab. Nice-to-have, not need-to-have.
The fine print that actually matters
- Depth and table: for rounds, depth ~59–62.5% and table ~54–60% is the classic sweet zone. Outside it, weight hides in the belly of the stone where you can't see it.
- Polish and symmetry: Excellent/Very Good is fine for both; don't pay extra beyond that.
- Fancy shapes have no cut grade. Ovals, pears, cushions, etc. aren't officially cut-graded, which is why 360° video is non-negotiable for them — you are the cut grader. See our shape comparison.
Can a great cut make a diamond look bigger?
Brighter, which reads as bigger. A well-cut stone lights up edge to edge; a deep-cut stone has a dim rim of wasted weight. Carat measures weight, not wow. More in carat sizes compared.
Is "hearts and arrows" worth it?
It's a symmetry pattern visible under a special viewer — proof of precision cutting. Beautiful, satisfying, invisible at dinner. Buy it if the premium is small or precision delights you.
Where we'd actually shop
The retailers worth your time for this decision:
Blue Nile
Massive inventory of GIA-graded natural diamonds and frequent sitewide sales. The default place to start a search.
James Allen
360° HD video of every single stone, so you can inspect the exact diamond — inclusions and all — before you buy.
Rare Carat
A price-comparison engine for diamonds — it pulls stones from dozens of vendors so you can see the whole market at once.
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