Diamond Polish and Symmetry: What Is Enough
By Josh Allen, Co-Founder of YourDiamondGuys.com. Fifth generation diamantaire with 30+ years in the global diamond trade. Former supplier to Tiffany & Co., Cartier, and Harry Winston.
Do not overpay for paper, diamond polish and symmetry matter, but the stone still has to look premium in the video.
Most buyers see polish and symmetry and treat them like small finish grades. Sometimes they are. Sometimes they are the clue that a stone being sold as premium precision does not deserve that price.
I always start with GIA for natural diamonds. Not because the cut grade alone is enough, but because GIA gives me proportions I can actually trust. Softer lab reports do not give me the same confidence in those numbers.
If a seller asks for a precision premium, I want proof that the diamond really deserves it. A pretty label does not make an uneven pattern disappear.
Most buyers do not need to obsess over finish grades. You just need to know when they support the price and when they expose a seller asking for too much.
What Polish Means
Polish is the quality of the diamond's surface finish after cutting. Poor polish can leave surface marks that affect transparency or crispness.
In many real buying situations, Excellent and Very Good polish can look the same to the naked eye. But for a premium round brilliant, I want Excellent.
What Symmetry Means
Symmetry is the precision of facet alignment and shape. It affects the pattern you see face up.
For round brilliants, symmetry matters because the pattern should be clean. If you are paying for top cut quality, Excellent symmetry is the right target.
| Grade | When It Can Work | When I Avoid It |
|---|---|---|
| Excellent polish | Preferred for stronger candidates | Rarely a problem |
| Very Good polish | Can work on value stones | Avoid when paying a cut premium |
| Excellent symmetry | Preferred for round brilliants | Needed for precision claims |
| Very Good symmetry | Can work in some fancy shapes | Avoid for Hearts and Arrows claims |
Why I Combine These Checks
Polish and symmetry are finish grades. They help. They do not replace the video.
The mistake is treating Excellent polish and Excellent symmetry like a free pass. They are supporting evidence, not the whole case.
For round brilliants, my starting screen is table 56 to 58 percent, depth 60 to 62.4 percent, crown angle 34 to 35 degrees, pavilion angle 40.6 to 41 degrees, Excellent polish, Excellent symmetry, and none to faint fluorescence.
My Call On Finish Grades
For a serious round brilliant purchase, require Excellent polish and Excellent symmetry. For fancy shapes, Very Good can be acceptable when the video is strong and the price reflects it.
Do not pay a premium for a diamond with finish grades that do not support the story being sold.
Reach out to Rob or me at YourDiamondGuys.com, or book your free consultation. We will look at the actual stone with you. No sales pitch.
Where Finish Grades Matter
Use polish and symmetry after the bigger question is answered. Does the diamond actually look good? If yes, the finish grades help you judge whether the price makes sense.
Mistakes I Would Skip
- Do not treat polish and symmetry as the entire cut grade.
- Do not pay a precision premium for Very Good symmetry on a round brilliant.
- Do not reject every Very Good finish grade in fancy shapes without looking at the video.
- Do not ignore pattern issues just because the report says Excellent.
Precision Premium Example
A Very Good polish grade on a value fancy shape does not always bother me if the video is strong and the price is right. A Very Good symmetry grade on a diamond being sold as a precision round is different. The claim and the grade have to match. If the seller wants a premium price, I want the finish grades and the video to match the story.
Questions I Ask About Finish
- What are the polish and symmetry grades?
- Is this stone being priced as a premium cut diamond?
- Can I see whether the face up pattern looks clean?
- Is Very Good finish reflected in the price?
Where I Would Compare Finish Claims
Use these sites as comparison tools, not automatic recommendations. I would compare similar stones on Ritani and Blue Nile, then judge each diamond by the report, video, spread, and price. If the stone is weak, the link does not save it.
Why Diamond Polish Matters
Questions? Reach out directly for a free consultation, or drop them in the Diamond Buyers Academy community — Rob and I answer personally.
Questions Buyers Ask Us
Think of diamond polish as the quality of the surface finish. It can affect crispness and transparency when defects are meaningful.
Diamond symmetry measures how well the facets align. It affects pattern precision and face up balance.
Yes, in some value situations. For a premium round brilliant, I want Excellent polish.
It can be acceptable in some fancy shapes. For round brilliants and precision claims, Excellent symmetry is the safer target.
No. They support the cut story. You still need proportions, images, video, and light performance evidence when appropriate.
*Some links on our site may earn us a small commission at NO EXTRA cost to you, helping us keep our content free*