why aren't diamonds cut to ideal proportions

Dop and tang used in diamond polishing.

Diamond cut is often highlighted as the most important “C” as it has the biggest impact on the diamond’s appearance. That’s because cut determines if a diamond will sparkle with life or appear dull and lifeless.

Out of the 4Cs, cut is also the factor that is solely decided by the actions of humans. And as obvious as it seems, I pretty sure everyone wants a diamond that looks brilliant and fiery.

Now, if all rough diamonds have the potential to be turned into beautiful jewels, have you ever wondered why the majority of diamonds in the market are poorly cut?

Why do diamond cutters polish rough stones to crappy proportions by choice when they themselves will not buy a diamond that looks lifeless? Isn’t that completely ironic?

Well, the main reason why most diamonds are cut to mediocre proportions boils down to one word: PROFIT.

Principles of Diamond Cutting – Effects on Appearance

diamond fire rainbow flashes of light

Diamonds are unique because of their exceptional ability to reflect and refract light. An ideally cut diamond reflects close to 100% of the light that enters through its table and crown facets. This reflected light is seen as sparkle, fire and brilliance by the observer.

A well cut diamond will also make a stone look larger than a poorly cut one of the same carat size, mask its color and hide clarity flaws.

When a stone is cut too shallow, a fraction of light will leave the stone through the pavilion facets. Likewise, if a stone is cut too deep, a fraction of light will leave through its sides instead of being reflected back into the viewer’s eye as brilliance and sparkle.

This is the reason why poorly cut diamonds often look darker and lack life.

Reasons Why Rough Stones Aren’t Cut to Maximize Light Performance

Contrary to popular belief, human errors aren’t responsible for poorly cut diamonds and there aren’t any impromptu decisions made on the polishing wheel.

When we are talking about millions of dollars being involved with procuring rough diamonds and polishing them, there isn’t room for errors in creating profitable end products.

You see, in the diamond business, the bottom line is to make money and rough stones are cut based on deliberate choices. During the cutting process, every rough stone is carefully analyzed and meticulously planned with the use of powerful computing systems.

When deciding how to cut a rough stone, economics and profitability are 2 factors that are always placed above everything else. A diamond’s price is most significantly affected by carat weight.

And because of this reason, both cutters and retailers have strong financial incentives to retain weight in a rough diamond at the expense of having an inferior cut.

If sparkle and beauty matters to you when buying a diamond, you should check out White Flash and Brian Gavin. These are 2 vendors that specialize in super ideal cut diamonds.

Case Study: How a Rough Diamond is Utilized in Real Life

planning how a rough diamond is cut
removing more rough material to get an ideal cut

Most cutters maximize carat weight instead of “sacrificing” weight for better cut.

To illustrate this, let’s say we have a rough crystal that weighs 3.00 carats. From this rough, it is possible to attain two 1.3 carat round diamonds with a cut rating of “good” and these 2 diamonds have a total market value of $30,000.

It is also possible for the same rough crystal to be used to create 2 ideal cut stones weighing 1.00 carat and 0.90 carats instead. In contrast, these 2 diamonds could only sell for a total of $22,000 even though they have better optical performance.

Besides the higher market value the first option presents, the “good” cut diamonds are cheaper to produce because less time and skilled labor are needed on the polishing table. Economically speaking, which option would you take if you were the business owner?

Sometimes, the cutter’s decisions are influenced by material flaws and the intrinsic shape of the rough diamond. For example, the location of inclusions in a rough can force cutters to polish the diamond in a particular manner such that the inclusions get removed.

Such decisions are usually made with the help of high-tech scanning equipment and visualization software. Ultimately, priority is always given to better sale-ability and overall value at the expense of cut quality.

Visual Differences of Round Diamonds With Different Cut Grades

gia very good terrible light return dark contrast

GIA Very Good Cut

generic gia triple excellent diamond mediocre light return

GIA Excellent Cut

ags ideal best cut quality round diamond

AGS Ideal Cut

Above are 3 diamonds that I selected to show you how cut quality can visually change the appearance of the diamond. Feel free to click on each of the images and interact with the video listings for yourself.

As you can see, the GIA Very Good cut is outright horrible as there is too much contrast under the table facet and it makes the diamond appear very dark looking.

The second diamond is a generic GIA triple excellent cut diamond which can be found in most jewelry stores. The problem with this diamond is that it has non-ideal cut proportions which causes light leakage and poor contrast patterning.

The third diamond is a top of the line AGS ideal cut diamond which displays superb contrast patterning and light return. These diamonds only account for less than 1% of the global polished diamond inventory.

Here’s a short video that shows various diamonds with excellent and very good cut ratings being compared side by side. Under various lighting conditions, you will be able to see why cut matters when it comes to sparkle and brilliance.



White Flash and Brian Gavin are vendors specializing in super ideal cut diamonds that are cut for light performance and precise craftsmanship. If you are looking for the best of the best, definitely check them out first!

Let’s Wrap Things Up: What Cut Grade Should You Buy?

Most jewelers take advantage of the consumer’s obsession with diamond carat size and their ignorance about cut quality in order to maximize their profit.

If you want a beautiful looking diamond engagement ring and you are on a budget, my advice for you is to compromise on aspects like color, clarity and carat weight. Never compromise on cut because it actually helps make up for each of these 3 aspects.

When you are choosing a round cut diamond, I recommend starting your search by looking at diamonds with a cut grade of either GIA 3Ex or AGS ideal 000 and using this table of ideal proportions to narrow down your selections.

Despite my advice, I know there will be some people who will intentionally sacrifice cut quality because they have a minimum requirement in carat weight to meet. With a limited budget to work with and an unwillingness to lower clarity/color specs, the only way for them to afford a larger diamond is to lower the cut quality.

If this sounds like you, please reconsider your options. I personally think that it is a bad idea to buy diamonds in this manner but the decision ultimately lies in your hands. If you want to spend your money on a dull-looking diamond, who am I to say you can’t?

vatche felicity pave diamond engagement ring in 18k white gold 4000 dollars

Quality matters over size. I purchased this stunning diamond ring recently from White Flash.

Lastly, the importance of a reliable gemological report (GIA or AGS) cannot be understated as it offers you an accurate assessment of the diamond’s material properties and cut quality. On this note, I want to point out that the different labs (e.g. GIA and AGS) take a slightly different approach to evaluating cut quality.

And since cut is such a major topic in the diamond selection process, I will discuss this topic in more depth on the next page…

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  1. Rodrigo-
    March 14, 2018 at 9:45 pm

    I being reading your webpage since a couple of months ago, when I decided I was ready to start looking for a ring to propose my girlfriend.

    Let me tell you that your webpage is the most complete and useful guide I have seen on the internet, and has made me be more conscious about the purchase I am going to do . Thank you for that.
    And as you probably hear everyday, I will try to get the best in my possibilities for the person I love.

    After having a good recommendation of a friend regarding James Allen, (where he bought her spouse ring), I thought I have everything solved. Great price and a direct friend recommendation.

    However , the more I have research, the more I panic regarding so many bad comments at Yelp and other opinion sites including yours, regarding James Allen quality, mainly regarding band quality and loose diamonds in short periods.

    I just wanted to know, in your experience and years on the business , if after all, are you still recommending James Allen site?

    The site itself is gorgeous, the zooms ,selection filters and everything makes me feel confident about what to purchase, however so many bad reviews regarding product quality makes me fear if over the time I am getting a poor quality product.

    If you think there are better site to look what would you recommend?

    I really appreciate your help.

    Just to provide some perspective of what I am looking :

    1. Round diamond
    2. Solitaire setting
    3. Budget : 5K

  2. Paul Gian-
    March 15, 2018 at 6:42 pm

    James Allen is one of my most trusted vendor with diamond shopping.

    What you mentioned has happened everywhere even with big brands like Tiffany, Cartier or any other store.

    When jewelry pieces do have issues (this is rare but has occurred with vendors like James Allen & Brilliant Earth), it usually pertains to the jewelry setting not being polished up well or had craftsmanship issues (i.e. slightly uneven prongs). Even in these scenarios, the diamond is perfectly fine and the ring can be sent back for “repairs” at the vendor’s cost.

    I will say again, this is really rare but things do slip by (especially at peak periods like Xmas) and screw-ups will happen from time to time. The most important thing is that vendors take responsibility which they do screw up. So, that actually wins points from me.

    With James Allen, you are in good hands. So, no worries there. In any case, you are protected by a money back guarantee (which includes free returns) for any reason the ring fails your expectations.

    This is a newly published article: https://beyond4cs.com/best-places-to-buy-diamonds/

    For yourself, I would say James Allen and white flash would be most suitable. But really, let the choice of settings decide whom to work with.

    From JA, this would be a diamond I would recommend: https://www.jamesallen.com/loose-diamonds/round-cut/1.01-carat-h-color-si1-clarity-true-hearts-cut-sku-4407583

  3. Rodrigo-
    March 18, 2018 at 2:53 pm

    Lastly, I Also noticed that the price of the diamond jumped up by $300 overnight. Is this usual? Should I hold off and wait? Do prices eventually drop? I was ready to purchase right now and noticed the difference.

  4. Paul Gian-
    March 23, 2018 at 8:23 am

    Diamond prices have been adjusting upwards since the beginning of the year. It has not dropped since they have been coming off really low prices for years. It’s pretty common when suppliers adjust their prices at cost basis.

    Anyway, you aren’t the only one. I have readers giving me this kind of feedback and of late, I am seeing this happen across many vendors in the industry too.

    Now, for this ideal cut diamond, https://www.jamesallen.com/loose-diamonds/round-cut/1.01-carat-h-color-si1-clarity-true-hearts-cut-sku-4407583, the price increase is seen on my end as well.

    As for where prices will go in near future, I really have no idea. If I could predict prices accurately, I would be using this expertise to trade shares and be making a killing. : )

  5. Rick-
    July 19, 2018 at 11:31 pm

    Have read your site and am a research oriented consumer. Hunting for that value (your premium stone example) would actually enrich the purchase for me.

    Looking for round stone. Engagement setting. Budget around 24k for the stone, but not that price conscience.

    Have poured over whiteflash’s inventory for CT 1.8-2.47.
    Have heard there is value in purchasing slightly below half carat sizes.

    Looked at all the cut above, many had significant scoring/defects on the face and other blemishes.

    Seems counter intuitive and that such blemishes would stand out as chips or scratches, and make the optical perfection less important when there is a major defect that attracts the eye.

    There were only two premium select stones. I used their default filters otherwise.

    I don’t believe H&A is the most important factor.
    For me, where the trade-off is negligible to the naked eye, I would rather visually clean. And recognize cut is the most important factor in brilliance, therefore do appreciate the sites that give the additional information to help assess.

    Accept that selection is a process of trade offs and do not require perfection. Blemishes in people and stones make them unique.

    Looking for your help if you still do this.

    I am an engineer and veteran, for what that is worth. Thank you for your time.

  6. Paul Gian-
    August 1, 2018 at 2:13 am

    Well, H&A affects scintillation patterning but there are diminishing returns if you compare the Expert selections to the ACA diamonds. It’s more of a psychology thing. But if you compare a generic gia 3Ex with an A Cut Above diamond, the differences are there.

    Most premium selects don’t meet my own standards and there isn’t any I can recommend in their inventory now.

    https://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3817256.htm this diamond should get you the best value for money and is eyeclean.

    If you want a diamond that faces up white and if you are color sensitive, then this would be the best buy:

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