The useful answer
Excellent doesn't mean identical.
Two GIA Excellent diamonds can have different proportions and still earn the same overall grade. The facets can show different patterns. One can look bigger, clearer, or brighter to you. That's why I look at the actual stones instead of stopping at Excellent.
We're comparing natural round brilliants here. Start with GIA, then put the report beside the actual images. Still narrowing the list? Use our GIA Excellent filter guide first. Once you've got two candidates, look closer at what separates them.
Two original examples
Look at the pattern, not just the word Excellent.
GIA calls both of these examples Excellent. Both show balanced bright and dark areas, but their proportions differ. Look at the diagrams and photographs together. They show room for different appearances within one grade, not which diamond you should buy.
Same category.
An even distribution of bright and dark areas.
Original educational figure: GIA. View GIA’s cut grade examples. These are not current inventory offers.
Different pattern.
A different proportion arrangement within the same overall grade.
Original educational figure: GIA. View GIA’s cut grade examples. These are not current inventory offers.
The side diagrams differ. So do the patterns in the photographs. But one still image can't show fire or sparkle through movement, or tell you how the stone looks in every room. You need to see it move.
Read the pairing
An angle needs its partner.
Don't buy a crown angle on its own. Read the pavilion angle with it, then look at the table, lower halves, stars, girdle, and how the facets meet. GIA's cut grade explanation covers how appearance, design, and craftsmanship fit together.
| Report field | Starting range or preference | What comes next |
|---|---|---|
| Table | 56 to 58 percent | Check the pattern and the balance of brightness and fire. |
| Depth | 60 to 62.4 percent | Compare the actual diameter with the weight. |
| Crown angle | 34 to 35 degrees | Read it with the pavilion angle, not in isolation. |
| Pavilion angle | 40.6 to 41 degrees | Ask for images showing the actual light return. |
| Polish and symmetry | Excellent | Keep checking appearance rather than stopping at finish. |
| Fluorescence | None to faint | Inspect the actual stone’s transparency in useful light. |
Those ranges are my starting filters, not GIA's definition of Excellent. Inside them? I still want to see the stone. Outside them? Show me why it works. Rounded measurements on a report can't describe every individual facet.
Read the crown and pavilion together.
Crown angle
Pavilion angle
The crown sits above the girdle. The pavilion sits below it. Their angles work together, so don't buy from one isolated number. GIA supplies these anatomy diagrams. Rob's narrower screening ranges above are buying preferences, not the complete Excellent grade limits.
Diagrams: GIA, round brilliant anatomy.
Compare like with like
Different studio setups can exaggerate the gap.
Ask for the same angles, exposure, background, and lighting. Put one diamond under spotlights and another under diffuse light and you've changed the test. Get a slow tilt of both in the same conditions.
Don't demand an all white photograph. A diamond needs contrast. Watch the bright and dark areas change as it moves. A broad area that stays dark deserves a closer look. One dark facet in a paused frame doesn't settle it.
Our two diamond video comparison includes real round diamond recordings and a checklist. Use it to see whether the clips answer your questions or whether you need a better view.
The stone beyond the cut grade
Clarity and transparency still get their own inspection.
Two Excellent rounds can differ because one has a distracting inclusion, haze, or a smaller visible spread. An overall cut grade does not erase those buying questions. Compare the length and width, then inspect the actual diamond at an agreed normal viewing distance.
Ask about any bruise, chip, cavity, knot, etched channel, or indented natural. Where is it? Does it affect durability? A tidy plot doesn't rule out haze, and a pretty arrows image doesn't answer those inclusion questions.
Hearts and Arrows images help you check optical symmetry when they show this exact stone through the right viewer. Don't assume all GIA Excellent diamonds have the same precision. And don't let a good pattern finish every other check for you.
How I would choose
Pay for the evidence that changes your decision.
| Finding | Useful response |
|---|---|
| Both have good reports, comparable images, and a look you like. | Compare visible size, inclusion visibility, complete price, and purchase terms. |
| One has much better documentation. | Value the reduced uncertainty, then request the missing evidence for the other. |
| One has a lower price but unresolved haze or persistent darkness. | Resolve the appearance concern before treating the discount as value. |
| The clips use incompatible lighting. | Ask for matched diffuse light and slow tilt views before naming a winner. |
If you want precision cut candidates with documented images, compare Whiteflash and Brian Gavin. Read the evidence attached to the individual stone. The retailer name and the report grade do not choose for you.
Send both reports, actual videos, optical images, dimensions, and complete quotes through Compare Two Diamonds. Josh or I can help work out whether the difference is visible, useful, and worth the money.
Buyer questions
Your questions, answered
Can two GIA Excellent diamonds have different proportions?
Yes. Excellent covers different proportion combinations. Look at how the actual stone performs instead of treating one number as the answer.
Are the ranges on this page GIA’s definition of Excellent?
No. They're our starting filters for natural rounds. GIA's Excellent category includes a wider range of combinations. The images and actual stone still get the final look.
Do the two GIA figures show which diamond I should buy?
No. They're teaching examples. They show how two Excellent diamonds can differ, not two current offers I'd tell you to choose between.
Does a dark area in the photograph mean light leakage?
No. It can be a reflection or part of the diamond's pattern. Ask for the right optical images and a video in matched lighting before calling it leakage.