If you had done some research into buying a diamond, you probably read or heard some stuff about the importance of symmetry grading and its impact on a diamond’s appearance. Very often, I receive emails from people seeking an opinion on the kind of symmetry rating they should look out for.

Should they only consider diamonds with excellent symmetry? Is a Very Good rating good enough? Is it necessary to buy a diamond with excellent symmetry to get the most beautiful stone?

Well, the answer to the above questions is: It depends.

To the layperson, the differences between a Very Good and Excellent symmetry rating are largely technical and not discernible by the naked eye. Unless you use a 10X loupe to inspect the diamond and know exactly where to look, you probably can’t see visual differences.

Does Excellent Symmetry + Excellent Polish = A Better Looking Diamond?

Logical thinking may probably tell you that precise facet alignments and luster would yield a diamond with better sparkle. After all, isn’t symmetry all about lining up the individual facets precisely to each other so that they reflect light properly?

But that’s a HUGE MISCONCEPTION!

The truth is, light performance is heavily influenced by the diamond’s proportions (crown angles, pavilion angles, table size and depth) instead of symmetry and polish.

Even if a diamond achieves excellent symmetry and polish, it can still appear lifeless and dull if the critical proportions are cut wrongly. Vice versa, if a diamond has only Very Good symmetry or Good polish, it is possible for it to appear brilliant and sparkly.

Case Studies: Correlation of Symmetry/Polish to Cut Quality

0.70 Carat – G Color – SI2 Clarity – Dismal Looking Round Diamond

diamond with very bad proportions

If you only saw the photograph of the diamond without the grading report, would you have imagined that GIA assigned excellent ratings for both the diamond’s polish and symmetry? And that’s precisely the point I want to make.

The symmetry and polish ratings of a diamond are an assessment of its finishing and NOT an indication of its cut quality and performance. In fact, this sorry-looking diamond was cut to extremely poor proportions and received only a “good” cut grade by GIA.


0.70 Carat – I Color – VS2 Clarity – Excellent Cut Round Diamond

ideal round brilliant with great proportions

In comparison, this diamond only received a “Very Good” rating for its symmetry grade. Yet, it looks a thousand times better than the first stone. The second diamond received an overall cut rating of “Excellent” from GIA and yet, it displays much better contrast patterning than the previous example.

If you compared these 2 stones side by side, I am pretty sure you immediately know which would be the hands-down winner. It’s going to be the one with better proportions even though it has a “Very Good” symmetry.

White Flash and Brian Gavin are 2 of the best vendors that specialize in super ideal cut diamonds. Check out their signature diamonds if you want the ultimate brilliance and sparkle for your engagement ring.

What About Super Ideal “Hearts And Arrows” Diamonds?

If you are thinking of buying super ideal hearts and arrows diamonds, then you need to understand that excellent cut, polish and symmetry ratings are “mandatory prerequisites”.

In order to achieve a beautiful patterning, the proportions and placements of each individual facet must be extremely precise. A little deviation in cutting proportions and finishing would result in undesirable effects on the diamond’s optical symmetry (h&a patterning).

Here, I want to bring to your attention that NOT every diamond with GIA triple excellent or AGS triple ideal ratings would automatically qualify it as a hearts and arrows diamond. I’m highlighting this issue here because many jewelers use the term H&A loosely to market subpar products to uneducated consumers.

The following excerpt from GIA’s Symmetry Grading Boundaries For Round Brilliant Cut Diamonds, shows you the degree of “tolerances” used in their grading system.

gia limits for estimating symmetry grades

Everyone wants to excel and be the best they can be. Diamonds are no different. Cutters and buyers around the world perceive a super ideal hearts and arrows diamond to be analogous to winning a gold medal in the Olympics. Very few can actually win it and stake claim to being the best.

For a diamond to achieve picture-perfect hearts and arrows patterning, it requires all of the proportion factors to be stricter than those acceptable for an excellent rating. For example, a round brilliant cut with a table size variation of 1.0%, a culet off-centered by 0.5% and a table off-centered by 0.4% will NOT result in nice looking H&A patterns.

Let me show you the types of diamonds that are usually marketed by jewelers as “H&A” stones.

gia 3ex yet poor symmetry

This diamond (GIA #6322242026) was graded with Excellent symmetry by GIA but it doesn’t possess poor optical symmetry. You can see the obvious twisting and deformation of the hearts and poor patterning in the image above.


d if hearts and arrows diamond poor symmetry

This next diamond is another one that is graded by GIA as a triple excellent diamond (Excellent cut, symmetry and polish) and yet it exhibits poor patterning and optical precision.

The shocking thing is that this is a D color, flawless diamond. If you asked me, it’s such a waste that a diamond with the best material qualities has been mired by mediocre cut quality.

Personally speaking, I’m a perfectionist when it comes to cut quality. Knowing that a diamond has been cut to the best possible standards gives me a better enjoyment of the purchase psychologically.

Let me show you an example of the type of diamond cut quality that I look out for. Click on the image and check out the scope images that reveal how well cut the diamond is.

1 carat g vs2 clarity super ideal cut diamond

Better cut quality + cut precision = better sparkle and brilliance!

As with everything else, a higher quality product is usually more expensive. To achieve such a level of cut precision, skilled labor is required and more material needs to be removed from the rough diamond during polishing.

So, the question you need to ask yourself is whether this increase in price is justifiable for improvements in light performance. I personally think it is. Ultimately, buying diamonds is largely a matter of personal preferences and what really matters is that you enjoy your purchase.

If you are like me and want the best sparkle for your diamond ring, check out White Flash and Brian Gavin. Cut to precise perfection, their signature diamonds are some of the most beautiful gems you will ever find in the market.

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4 Comments

  1. Avatar
    propdevel-
    January 26, 2016 at 1:48 pm

    A very good article about the ins and outs of diamonds. I have been researching for over 2 years and it taught me about some issues that I would otherwise not known.

    What I have learnt is that its a mine field out there and you can trust NO ONE! So chose carefully and take your time.

    I have one question.

    You recommend AGS diamonds regularly and they seem to have a higher standard of cut quality compared to GIA diamonds. Is it safe to say that all AGS ideal diamonds will have perfect symmetry?

  2. Avatar
    Paul Gian-
    May 4, 2019 at 2:56 pm

    You are right that the better cut diamonds get sent to AGS for grading. AGS does offer a more indepth cut assessment compared to GIA but that doesn’t mean everything that comes out of the lab is top notch.

    gia excellent symmetry near perfect hearts

    This diamond was graded with ideal symmetry by AGS but it doesn’t possess ideal optical symmetry. You can see the obvious twisting and deformation of the hearts in the image above. So, it depends on a case by case basis.

  3. Avatar
    Justin-
    June 27, 2019 at 12:38 am

    Hi Paul,

    Thanks for the great site! I have an inherited diamond ring that I am considering using to propose.

    Key information:
    Cut — Old World European (Edwardian)
    Color – H
    Clarity – Si2
    Carat Size – 2.54

    Polish — Good
    Symmetry — Fair

    The stone is set in a platinum Edwardian style setting that my appraiser suggested had value for the craftsmanship.He cautioned that due to the size and flaws in the stone, getting it placed in a new setting would risk enhancing the flaws in the stone and looking “cheap”.

    As such, he ultimately advised that I keep everything as is.

    Prior to today’s appraisal, I was considering getting the ring placed in a new, shinier setting, such as a Halo or Pave. Now I am filled with doubt about tinkering with anything, or about using a flawed stone (despite the appraisal suggesting considerable retail value…)

    So I’m here to ask: What would you recommend? Keep it all as is? Get a new setting? If so, any settings that could help mask the flaws? Am I worrying too much over the SI2 Clarity and the relatively low polish / Symmetry? Can I do anything to fix these? Is polish or symmetry more important in a diamond?

  4. Avatar
    Paul Gian-
    June 27, 2019 at 3:44 am

    Vintage diamonds have terrible symmetry and polish that’s inherent to the kind of equipment and knowledge cutters have at that time. At the end of the day, it really depends on your personal preferences. If you like a vintage appearance, stick with the current setting. If you hate the current setting, then there’s only one way forward and that is to change the setting. There’s nothing much you can do about the clarity or cut quality unless you get it recut. In which case, getting a new diamond all together would be a better solution to save money and hassle. In terms of appearances, symmetry is generally more important than polish in the sense that you can visually see an off-shaped diamond outline. Polish is generally less observable unless it is in the terrible ranges of Fair and Poor.

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