Significance of Diamond Depth And Table Percentages

depth and table percentages for diamonds

This Diamond Has a 62.5% Depth

The depth of a diamond is its height (in millimeters) measured from the culet to the table. On a grading report, there are normally two measurements of depth – the first is the actual depth measurement in millimeters (shown under ‘measurements’ at the top of a grading report), and the second is the depth percentage (see image on left), which shows how deep the diamond is in relation to its width. 

Today, the art of polishing diamonds had become somewhat scientific. That said, even though the depth percentage can be a tell tale sign for brilliance and value (stones that are cut too deeply are usually cut to retain weight from the rough), it doesn’t tell the entire story. You will find out why as I explain things in more details.

Extreme Depth Proportions Can Affect Sparkle

The place where that depth lies is also crucial in determining the diamond’s beauty. The pavilion, in particular, should be cut at correct proportions so that light rays can bounce around within the diamond and be reflected out at the proper angle to meet an observer’s eye.

extreme shallowness in depth
total depth over 65

Total depth percentages of 56.6% (left) and 65.9 (right) are recipes for disastrous looks.

The ideal depth percentage varies with the shape of the diamond. A depth percentage that may be too much for one shape might be essential for another. For instance, a princess cut with a 75 or 77 percent depth would still be considered acceptable and can yield an attractive diamond. On the other hand, a depth of 65 percent for a round diamond would be excessive and be detrimental to its beauty.

The Importance of Table Percentages And Values

diamond table percentages

This Diamond has a 54% Table

The table refers to the flat facet of the diamond which can be seen when the stone is face up. It also happens to be the largest facet on a diamond and plays a vital role on brilliance and light performance of a stone.

The main purpose of the table facet is to refract light rays entering the diamond and to allow reflected light rays from the pavilion facets back into the observer’s eye.

It is widely misconceived that a larger table percentage would make a round diamond more brilliant than one with a smaller table. However, this is not the case as there are other factors that contribute to the overall brilliance and fire of a diamond.

Fire is best observed at the bezel facets of a diamond. With a finite amount of space at the crown area, having a larger table would mean that bezel and upper girdle facets would now have less surface area and dispersion decreases. Vice versa, having a small table would allow girdle facets to disperse light more effectively while suffering from issues with brilliance.

It is therefore important to strike a balance between light transmission through the table and color dispersion through the crown and upper girdle facets. As they say, too much of a good thing may do more harm than good.

huge table unsightly
small table high fire

An insanely huge table of 81% will make the stone on the left devoid of dispersion properties.

How is Table Percentage Calculated?

In a grading report, table percentage is calculated based on the size of the table divided by the average girdle diameter of the diamond. So, a 60 percent table means that the table is 60 percent wide as the diamond’s outline.

If a diamond is round, gemologists can compute this value by dividing the table diameter, measured in millimeters by the average girdle diameter. For a consumer, this can easily be calculated based on the average measurements found at a grading report’s top left-hand side.

For fancy shaped diamonds, table percentage is computed by dividing the table width (measured at the widest part of the facet) by the width of the widest part of the stone measured in millimeters. On a grading report, this width is the second of the three values under “Measurements” and is delineated in millimeters.

How to Use Depth And Table Percentages Effectively

Combined, the depth and table percentages of a diamond play a major role on the stone’s beauty. It shows you how the stone has been cut in relation to its proportion and is usually one of the first few values to help you instantly weed out diamonds with less ideal cuts.

While the variations in brilliance and sparkle may be apparent to the eye, the subtleties of proportioning may not be easy to discern.  Here’s the limitations imposed by numbers on a piece of paper. Even if a diamond has values that lie within “ideal” ranges, the diamond still requires additional performance data to determine its cut precision. We’ll show you how to select a diamond correctly in this guide here.

Also, while a diamond’s spread will be affected by its table width, choosing the best personality is a matter of personal taste ultimately.

If you are looking for ideal cut diamonds that are cut to the best proportions and precision, check out WhiteFlash.com and BrianGavinDiamonds.com. Their signature diamonds are subjected to a stringent quality control process and breathtakingly beautiful!

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30 Comments

  1. Kristine-
    January 4, 2015 at 6:48 pm

    I need to replace a stone from an eternity ring. I was told I need a 4.1 mm round stone, S1-I1, g or j color. What would you recommend? Thank you.

  2. Paul Gian-
    January 5, 2015 at 12:23 am

    Doing a proper replacement for a stone from an eternity ring is tricky. It is best to get your jeweler where you bought the diamond to do the the replacement. Basically, you need to match the table size and physical dimensions to the rest of the ring. Without looking at your ring, I can’t make a proper recommendation in this scenario.

  3. Ash-
    January 6, 2016 at 9:18 pm

    Hey Paul… great site! I’ve been told that having a depth value less than table will result in a darker diamond. Is this true? Most other things being equal, would one choose a diamond with greater relative depth or table? I’m comparing two very similar stones, one D61.1/T57 (E) and another D58.5/T62 (F). Thanks!
    (corrected)

  4. Paul Gian-
    January 7, 2016 at 3:12 am

    The statement isn’t always true. It depends on a case by case basis.

    From what I can tell, the F diamond isn’t going to perform well. The excessively large table size will result in a fisheye that would be easily observable with a little tilt.

    That said, while the E diamond has decent looking proportions, it is by no means a basis to conclude that the stone is going to be well cut.

    https://beyond4cs.com/buying-diamonds-blind/
    https://beyond4cs.com/shapes/round/ideal-proportions/

  5. Sam-
    February 2, 2016 at 4:22 pm

    Hello Paul,

    I am in the process of buying a diamond and stumbled across your website. You have so much great information. Thanks for making it available for the rest of us.

    I have found a diamond that I think is a good deal. After some reading on your site though, I am afraid that the diamond is cut too deep.

    It is 3.08 (J). The table is 56 and the depth is 62.3. The cut grade is excellent however. Thoughts? Thanks in advance.

    Sam

  6. Paul Gian-
    February 3, 2016 at 12:05 am
  7. Jon-
    June 2, 2016 at 7:24 am

    Hi Paul,

    I came across these 2 diamonds on James Allen and was stumped by what I saw in the Idealscope images.

    – jamesallen.com/diamonds/G-SI1-Ideal-Cut-Round-Diamond-1500331.asp
    – jamesallen.com/diamonds/I-VS2-Ideal-Cut-Round-Diamond-1493120.asp

    ( Update: These 2 diamonds had been sold and removed from JA’s listing. )

    First of all, I want to mention that I had read through your entire site on choosing a diamond. Great stuff. Good information. However, this particular phenomenon was not covered in your articles. Perhaps you did and I couldn’t find it. If that’s the case, could you point me in the correct URL.

    Here’s my question: Why is the Idealscope image for the G SI1 diamond so weird looking? It has alot more blacks than the usual Hearts and Arrows I had seen on your website.

    idealscope image with alot of dark triangles and black areas

    By comparison, I picked out an I VS2 and now, the idealscope image looks ‘normal’ to me.

    comparison of round diamond with different depth and table %

    Could you shed light on this? And theoretically, which diamond would be a better choice if I were to pick one?

    Thanks,
    Jon

  8. Paul Gian-
    June 2, 2016 at 11:01 pm

    Hi Jon,

    Thanks for your question. I think you have a very observant eye. Not many people would have observed this when looking at diamond details. From the Idealscope, both diamonds are showing excellent optics with tons of reds and minimal whites.

    For the G colored diamond, we see alot more areas of black which relates to more contrast in the diamond. This phenomenon occurs when the diamond has a depth % that is less than the table %. In this particular diamond, the depth is 58.4% and the table is 61.0%. Technically speaking, the difference is really due to a combination of star facet lengths, lower girdle facets, table size and depth proportions.

    For the I colored diamond, the depth % is higher than the table %. This results in the kind of Idealscope images you will see in the reference chart for light performance.

    Hope this helps,
    Paul

  9. jon-
    June 3, 2016 at 7:25 am

    Hi Paul,

    Jon here again. Thanks for the super fast reply. I really appreciate it. Since the G colored diamond has more contrast, will this impact the brilliance of the stone?

    If you were given a choice between these 2 diamonds, which would you pick and why?

    Jon.

  10. Paul Gian-
    June 4, 2016 at 12:07 pm

    Dear Jon,

    While it is true that the G colored diamond will be more contrasted than the I colored diamond, I believe that when both diamonds are placed side by side to each other, the difference in contrast will NOT be easy to detect. To the untrained eye, these 2 diamonds will appear similar to each other.

    However, to the trained eye, you can probably pick up the scintillation patterning from the G colored diamond. That is caused by the additional black areas you see in the idealscope image. However, there is a tradeoff here. The fire and dispersion of this diamond might not be as high as that of the I colored stone.

    Assuming that I would have to make a choice between these 2 diamonds, it is a balance between getting value for money versus cut quality. Strictly speaking, the I color diamond is better cut and has a better balance of fire vs brilliance.

    Since I do value color, I would go for the G colored diamond and I say this with the caveat of my personal preference. In terms of face up size, the physical measurements are very close to what the I colored diamond offers. Also, there is only a price difference of about $150 between these 2 diamond. However, the G colored diamond is 2 grades better in color than the I colored stone.

    This means that the G colored diamond will appear relatively whiter. To me, this is what most people would be able to observe when looking at your ring. The slightly higher price of $150 is justifiable for a 2 grade color jump.

    Hope this helps,
    Paul

  11. Chris-
    July 1, 2016 at 1:40 pm

    Is it ever a good idea to purchase a diamond with a table width which is larger than the diamond’s depthnin regards to round diamonds. Thanks.

  12. Paul Gian-
    July 1, 2016 at 2:49 pm

    Depends on the diamond’s shape and what you are after. In general, no.

  13. Andrew Gioulis-
    August 17, 2016 at 6:46 pm

    Hi Paul,

    I have a jeweler that is trying to sell me this diamond for $3900:

    BR 1.01 E SI2 EGLNY

    Depth: 62.3
    Table: 59
    Culet: N
    Girdle: TN-STK
    Polish: G
    Sym: G
    Fluor: M
    Cut: G

    Is that a good price?

  14. Paul Gian-
    August 18, 2016 at 5:16 am

    Run! Poorly cut diamond plus a scammy report from EGL is a sure fire way to get ripped off.

  15. Chris L-
    September 8, 2016 at 9:45 am

    Hi Paul,

    Thanks so much for the extremely helpful information for beginners like me.

    Grateful if you may let me have your views on the following questions:

    1. A shop is showing me diamonds and what they say are the GIA certificates of these diamonds. Is there any way I could verify that the diamond shown to me is indeed the diamond mentioned in the GIA certificate. Is the “Inscription(s): GIA 2228540824” relevant? If so, where can I find the inscription in the diamond?

    2. I am convinced by you that cutting is the most important aspect. Is the cutting of the diamond GIA 2228540824 (1.20 carat, excellent cutting) brilliant by the numbers of the dimension of the diamond?

    Thank you very much

  16. Kelly-
    September 29, 2016 at 1:14 am

    Hi Paul,
    I am doing a report on diamonds and was given a data set with different buying factors. Among those factors are the depth and table (both as the proportions you describe). I know you want to be around 60, but what is the lowest ratio you can have for depth and table? For example, in our data set we have some observations that have the table of 6 or 126. For depth we have some numbers around 4, are these possible? The majority of our data is around 60, so we are thinking it is a user input error.

    Thank you for your help,

  17. Paul Gian-
    September 29, 2016 at 2:43 am

    Well, your data’s headings are definitely erroneous. There’s no way a table% can be more than 100%. For that matter, I also haven’t seen diamonds cut to table percentages of 6%.

  18. Mim-
    October 24, 2016 at 10:50 pm

    Hi Paul,

    Question: I’m trying to match .4 pointers to make four stone ring.
    Diamonds sourced for me by seller are all GIA triple excellent (have seen certs):

    .41 carat(4.74 x 4.76x 2.96) Table 58%, E,VS1
    .42 carat (4.76 x 4.79x 3.01) table 56% E Si1
    .41 carat (4.71×4.73×2.96) Table 57%, F, VS1
    .41carat (4.75×4.77×2.94) Table 59%, F Si1

    Do you think these would be good match for 4 stones? I’m a little concerned that the difference on table sizes is 3% or maybe that won’t matter on Diamonds this small when placed together. I’m (perhaps incorrectly) not that concerned about the colour and clarity differences as I feel they will not be noticeable and I have a budget to stick to. I am also assuming that the overall performance of the diamonds would be very good given that they are all certified GIA triple Ex. Any help appreciated.

    Thanks
    Mim

  19. Paul Gian-
    October 25, 2016 at 4:41 am

    Color and clarity won’t matter. However, I can tell you that a couple of diamonds down there with table sizes larger than 57% will never make it pass my own standards if I am buying the ring for myself.

  20. Sherry-
    February 1, 2017 at 11:46 pm

    Can I figure out the depth percentage of a diamond from its measurements?

  21. Paul Gian-
    February 2, 2017 at 2:19 am

    Yes you can. A simplistic way of doing this is to use the formula: (total depth ÷ avg. diameter) x 100%https://beyond4cs.com/wp-admin/edit-comments.php#comments-form

  22. Eddie-
    February 27, 2017 at 3:59 pm

    Hi Paul,

    Which is more important or how to rank the importance?

    Table, Depth, Crown Angle,Pavilion Angle

    I’ve been looking at several diamonds. Couldn’t make up my mind on based on the ideal proportions, most of them have crown angle at 35.5 but the rest is ok. It is safe to say crown angle 35.5 is ok?

  23. Paul Gian-
    February 28, 2017 at 4:47 am

    Any proportions that are outside of my recommended ranges are instantly rejected: https://beyond4cs.com/shapes/round/ideal-proportions/

    There are so many available stones to choose from and even if they meet the requirements and numbers here, that’s just the first step. I would follow up with asking for tangible cut data to analyze the diamond.

  24. Carole-
    March 13, 2018 at 12:05 pm

    Hi Paul. I have lost the stone out of my engagement ring. after looking at diamonds at a local jeweler, we have ascertained it is an old cut diamond, as it was raised and not flat at the top, after looking at the brilliant cut ones which are flat.

    Can you tell me what I should be looking for to get the similar diamond? Sorry for the ignorance. I have been offered a
    0.73 carat old cut stone quality G/Vs1.

    Carole

  25. Paul Gian-
    March 13, 2018 at 3:55 pm

    Sounds like you are in for a deal that gets you ripped off. Who graded the diamond as G/VS1? If it comes with a NON-GIA certificate, then that confirms it.

  26. Kevin-
    May 17, 2018 at 11:16 am

    Hi Paul,
    It is really eye opening to read the vast amount of unbias info you provide here. Thank you. (I only wish I had read this 15 years ago when I bought my first diamond ring!)

    I have been offered a opportunity to buy a 1.22 carat tiffany diamond ring. (assuming T&C certificate is accurate)

    F, VS1

    From what I have read, only 2 criteria are out:

    Polish: Very Good (Ideally excellent)
    Table size%: 58% (Ideally 54% – 57%)

    All other cut proportion parameters falls within your stricter range.

    I know you said, any deviation, the stone should be rejected….
    Here in Australia, I don’t know if we have as much choice as in US especially in the secondary market.
    How would these two parameters affect the performance against a stone that is ideal?
    Thank you.

  27. Paul Gian-
    May 17, 2018 at 11:46 am

    It really depends on how the individual facets work together for light performance. When the proportions are right, the chances (probability) of that happening are better. The key is to look at tangible data like the ASET/Idealscope images.

    https://beyond4cs.com/2014/12/aset-reference-charts/

    And just to be clear, most people assume that Tiffany diamonds are top notch. They aren’t and you clearly see why here. If a jewelry business really cared about “best quality”, there’s no way they would allow the basic stuff like symmetry/polish to be second rate. They have a good brand name and that’s really all.

  28. Kevin Yang-
    May 17, 2018 at 1:07 pm

    Thank you very much Paul,
    I am so disillusioned.
    Can I just give you all the info, if its a AVOID, I will never speak of it again…

    1.22 carats F, VS1
    Precision of cut: EX
    Polish: VERY GOOD
    Symmetry: EX

    Total depth %: 61.6
    Table size %: 58
    Crown height %: 14.7
    Crown Angle: 34.2
    Star length % 50
    Pavilion Depth % 43.6
    Pavilion angle: 41.1
    Lower half length %: 75%
    Girdle thickness: Medium to slt thick

    Like you mentioned, thought I can’t go wrong with a T&C…

    I am also shocked to find another T&C 1.52carats D,IF ring priced 3 times as the one I m looking at failed all but 3 criteria out of the 12!

    Prior to tonight, I have never heard of ASET/Idealscope images. May I ask can this be done once the diamond is already on the ring? (I am so intimidated by the so called “experts” here in OZ, I am surely going to be made to feel absolutely inadequate when I mention about this technology tomorrow! Lol).

  29. Paul Gian-
    May 17, 2018 at 4:39 pm

    This can be done on a mounted ring. Here’s an example: https://beyond4cs.com/reviews/blue-nile/signature-diamond/

    With T&C, you don’t get the terrible diamonds like out in the market but you don’t get the great stuff either and the prices are steep.

    https://beyond4cs.com/reviews/tiffany/

    For what’s its worth, you actually don’t need to buy the scope as the better jewelers who are transparent offer them in their listings.

    https://beyond4cs.com/best-place-to-buy-engagement-ring/

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