ASET Reference Charts For All Types of Diamond Shapes

In an effort to help you better understand what to look out for in an ASET image, I had compiled some images of diamonds with various levels of optical performances. Feel free to make comparisons of your diamond’s ASET against those listed below and you’ll quickly find out how well it returns light.

Here’s a quick explanation of what the different colors represent:

Red: intense light return – red is generally what you want to see.
Blue: contrast – important for contrast and scintillation. Blue areas should be as symmetrical as possible.
Green: less intense light return – keep green areas minimal.
Black/White: light leakage – keep black/white areas minimal.

If you are buying online, vendors like James Allen, White Flash and Brian Gavin are all great places to start your shopping as they provide indepth information about their listings. On top of that, you also get a massive selection of AGS and GIA graded diamonds for you to cherry pick from.

ASET Reference Charts For Round Brilliant Cut Diamonds

Average – Mediocre

asets of poorly cut round diamonds

Above Average – Very Good

examples of good round brilliant cut ASETs

Best – Excellent

aset chart of round diamonds with excellent optics 

There are only a few vendors in the entire world that cut round diamonds consistently to the best standards and performance. If you are looking for a diamond with maximum sparkle and life, head over to White Flash or Brian Gavin for them.

ASET Reference Photographs For Princess Cut Diamonds

Average – Decent

ags poor princess cut diamond asets

Very Good – Above Average

very well cut princess cut diamonds aset

Ideal – Best

ags000 princess cut aset 

James Allen, White Flash and Brian Gavin are recommended vendors for ideal cut princess diamonds. If you are looking for a bright and brilliant stone, their signature collection is the place to start browsing.

ASET Image Examples For Cushion Cut Diamonds

Average – Mediocre Light Return

aset images for poor optical performance cushion diamond

Above Average – Very Good Light Return

aset images for average optical performance cushion

Strong – Ideal Light Return

aset images for ideal optical performance in cushion cuts 

When it comes to cushion cut diamonds, both James Allen and Blue Nile are recommended for their wide range of selections. This allows you to cherry pick the best diamonds for their optical performance.

ASET Pictures For Oval Diamonds With Different Light Performances

For fancy shapes like ovals, pears and radiants, you shouldn’t be expecting to see saturated reds (like those in ideal cut rounds) throughout the entire ASET image of the diamond. Due to the nature of how light works, light leakage (white) will be seen even in the most well-cut stones.

Average – Mediocre Optics

aset of leaky oval shaped diamonds

Above Average – Good Optics

aset of OK oval shaped diamonds

Excellent – Strong Optics

aset of excellent brightness oval shaped diamonds 

For oval shape diamonds, a bow tie can make or break their beauty. Vendors like James Allen and Blue Nile are the best places to shop at because their video listings enable you to perform proper analysis.

ASET Reference Charts For Marquise Diamonds

Average – Mediocre

aset photographs for marquise diamonds with poor light performance

Above Average – Very Good

aset photographs for marquise diamonds with very good light performance

Best – Excellent

aset photographs for marquise diamonds with ideal light performance 

Shape appeal and strong light return is crucial when selecting a marquise diamond. I recommend retailers like James Allen and Blue Nile as they have the inventory depth for you to cherry pick the best stone within your budget.

ASET Reference Charts For Pear Diamonds

Average – Mediocre

aset examples of poorly cut pear diamonds

Above Average – Very Good

aset examples of very good cut pear diamonds

Best – Excellent

aset examples of excellent cut pear diamonds 

The outline of a pear shape diamond is a key factor that affects its appearance. It’s extremely important to see the diamond in neutral lighting prior to purchase and that’s why shopping at James Allen and Blue Nile is your best chance to find a perfect diamond.

ASET Reference Images For Emerald Cut Diamonds

Bad Optics – Poor

emerald-cut-diamonds-aset images indicating extraneous light leakage

Very Good – Above Average

emerald cut diamonds aset images showing ok optics

Best – Excellent

emerald cut diamonds aset images excellent optics 

When buying emerald cut diamonds, you need to pay attention to the scintillation patterning and how the facets interact with light. For the best results and selections, I recommend shopping at James Allen and Brian Gavin.

ASET Reference Images For Asscher Cut Diamonds

Bad Optics – Poor

asscher cut poor light performance aset

Very Good – Above Average

asscher OK light return aset

Best – Excellent

asscher cut ideal quality optics aset photo 

Besides a strong looking ASET image, the scintillation patterning of an Asscher diamond is also important in its appearance. Vendors like James Allen and Blue Nile offer video listings to help you SEE exactly what you are buying.

ASET Reference Charts For Radiant Cut Diamonds

Poor – Average

asets of crushed ice radiant cuts with alot of light leakage

Good – Above Average

aset images of crushed ice radiants with good performance

Best – Excellent

ideal optics for well-cut radiant diamonds asets 

Most radiant cut diamonds in the market are cut to mediocre performance and have leaky centers. When shopping for them, I recommend checking out James Allen and Blue Nile to find your perfect diamond.

ASET Reference Charts For Heart Shaped Diamonds

Average – Decent

aset for poorly cut heart shaped diamonds

Above Average – Very Good

aset for very good cut heart shaped diamonds

Best – Excellent

aset for excellent cut heart shaped diamonds 

Heart shape diamonds are notoriously hard to shop for. I recommend both James Allen and Blue Nile for their broader inventory depth and their video listings to help you make an educated purchase.

If you need a second opinion about an ASET image, feel free to contact me personally via email. Do remember to include as much details as possible including the grading report, listing URL, images, videos and etc…

Share This Page on Social Media!


  1. Thiago-
    May 4, 2015 at 10:31 am

    My problem is that I am Red/Green color blind and trying to translate the Angular Spectrum Evaluation Tool photos is next to impossible for me. Would it be possible for you to help me analyze the pictures?

  2. Paul Gian-
    May 16, 2015 at 2:16 am

    Sure! Send me all the information you have (reports, pictures, photographs, urls) and I’ll let you know what I think about the stone’s performance.

  3. Judy-
    January 5, 2016 at 8:13 pm

    Hi Paul, I am interested in this James Allen stone but the sales rep says there’s no ASET or Ideal Scope image available. Should I go ahead and buy?:

  4. Paul Gian-
    January 6, 2016 at 5:56 am

    This diamond looks great. I can tell you that the idealscope image of this diamond will be awesome even if James Allen can’t capture the image on your behalf. Go for it! I’m sure you will be thrilled to see the stone in person.

  5. Emma-
    February 13, 2016 at 5:54 pm

    Hi there
    I love old diamonds- Edwardian , Giorgian ones- I prefer ones that have a soft light and sort of just twinkle rather than blinding me with their laser beams- I even like when they seem a bit grey ( not crazy about the yellow looking ones though)
    Do you have advice for buying antiques?

  6. Paul Gian-
    February 14, 2016 at 2:31 pm

    Sign up for our newsletter. I have a pending write up on antique jewelry in the coming months.

  7. Jerry-
    April 23, 2016 at 12:31 am

    Paul, whats your opinion on this pair? Should I be looking for symmetry in these images?

  8. Paul Gian-
    April 23, 2016 at 5:27 am

    I think it’s a great pair. When choosing matching earrings, the overall size, table and depth percentages of the diamonds should be relatively close to each other. I think you did well and Brian Gavin’s signature diamonds are top notch.

  9. Jerry-
    April 23, 2016 at 1:20 pm

    Thanks Paul! One more question please. Thiis pair looks better on paper as far as symmetry is concerned. One is VS1 and one is VS2, what is your opinion on the inclusion on the VS2 please? Is this a better choice? Thanks!

  10. Paul Gian-
    April 23, 2016 at 4:37 pm

    The differences are negligible. This is a great set as well.

  11. Neil-
    May 23, 2016 at 12:18 am
  12. Paul Gian-
    May 23, 2016 at 3:05 am

    Yes it is. It’s well cut. One word of advice though, if you don’t need D color and IF clarity for symbolic reasons, it’s just a waste of money to pay for these features.

  13. El-
    May 30, 2016 at 11:19 pm

    Hi Paul,

    Thank you so much for your wealth of knowledge. Wondering your opinion on this stone: Furthermore, what is your top advice for purchasing in person from Brilliant Earth? I don’t know if they will have an Idealscope or AGS ASET scope diamond analysis available so I almost feel like I would be even more blind than online. Thanks!

  14. Paul Gian-
    May 31, 2016 at 8:13 am

    This is a well cut diamond. As far as I know, Brilliant Earth does not have ASET imagery capability in their showrooms. Anyway, you don’t need an ASET if you know what to look out for.

  15. AG-
    June 4, 2016 at 12:13 pm

    Hi Paul, Your website has been a great help on getting to know the basics. I have found an emerald and would very much like your opinion for the cut and if it’s a good value diamond. I have requested the ASET chart cause I find it difficult to spot if it’s symmetric and well cut.


  16. Paul Gian-
    June 4, 2016 at 1:17 pm

    I reviewed the diamond here and I think it is a well cut emerald shape.

  17. JZ-
    June 7, 2016 at 9:59 pm

    Hi Paul. I am looking at this. What do you think the quality and value. Thanks

  18. Paul Gian-
    June 8, 2016 at 2:25 am

    It’s a decent diamond in terms of cut. However, it’s not a diamond I would buy because:

    1) Crown angles are too high. There are much better diamonds available.
    2) It’s an IGI diamond. Stick with GIA or AGS instead.

  19. AW-
    June 30, 2016 at 12:53 pm

    Hi Paul,

    Great website so many thanks for your time and effort in making a site where normal consumers can get a better understanding of the diamond industry.

    With the ASET picture from AGS how important is the symmetry? I am looking at the following stone from White Flash with SKU 3580108

    While it has an ideal cut and symmetry from AGS report the ASET seems off. Should I be concerned with the report or would it be good to have WhiteFlash inspect the stone.


  20. Paul Gian-
    June 30, 2016 at 3:23 pm

    The diamond is from the virtual inventory and White Flash doesn’t own it. From the report, it is clear that it doesn’t have good optical symmetry.

    If you are looking for the best of the best in terms of sparkle, go to: and do a search by selection the checkbox “In-House”.

  21. Kate-
    July 23, 2016 at 9:10 pm

    Hi Paul,

    I’m thinking of getting this stone but ASET and IdealScope images aren’t available, what do you think? I’m looking for a stone with great light performance and at least 7x5mm


  22. Paul Gian-
    July 24, 2016 at 12:16 pm

    It’s a well cut diamond. The patterning on that emerald cut is fantastic!

  23. James-
    August 1, 2016 at 4:57 pm

    Hi Paul,

    Do you know where I can buy an ideal scope or preferably an ASET? I’ve been looking on the internet but could not encounter.


  24. Paul Gian-
    August 2, 2016 at 6:01 am
  25. Christian-
    August 31, 2016 at 5:56 pm

    Dear Paul,

    I know I’m bombarding you with requests these days… sorry and thanks! (but it’s your fault ;-) because your brilliant website made me so curious and perfectionist about diamonds that I can’t stop and chose the final one).
    Would you also mind giving me your view about these two:

    1. SKU O100-319503126
    2. SKU O100-319503126
    3. SKU O103-030348605

    (this one is a bit weird…only VG symmetry and polish; slightly to very thick girdle… but the ASET looks very nice to me)

    Thanks very much!

  26. Paul Gian-
    September 1, 2016 at 4:00 am

    The shape appeal on the third stone isn’t great. I would dump that.

    These would be 2 diamonds that I would recommend:

    1. SKU O100-319503126
    2. SKU O108-383938738

  27. Alan.-
    September 6, 2016 at 9:58 am

    Dear James,

    Thank-you SO much for your expertise and, above all, your passion. You have helped to steer me away from a purchase that I was previously set on (which turned out to be horrible in the end).

    Through your help, I have taken some of your pointers on board and have narrowed my choice of diamond down to this one from James Allen to the best of my ability.

    Thought process behind this selection:
    1. Looking for a round brilliant with a carat ~1.25-1.35, IF clarity (for symbolic purposes)
    2. Minimum triple excellent as per GIA; especially not taking anything less than ‘excellent’ for cut (as ‘cut is king’)
    3. Used HCA tool to rule out any diamonds with a score >2.0 (for reference this one is 1.6 with excellent scores for light return, fire, scintillation and very good score for spread)
    4. Ensured high definition, minimum 10x magnification videos to ensure that I am not picking blind
    5. With the video/images and an untrained eye, I compared for optimal contrast and symmetry

    I asked for Idealscope/ASET scope images but the sales rep (similar to many above) said that they were unavailable until AFTER a monetary transaction. Is this an acceptable proposal? Would this be a good/great diamond to take the leap of faith for?

    Please let me know as I currently have the diamond on hold :).

    Thank-you so much again for all your help, I really appreciate your time and efforts.


  28. Alan Nguyen-
    September 6, 2016 at 11:21 am

    Dear Paul,

    I hope this post finds you well! I was hoping to get some advice re: this stone that I have narrowed down for selection following a really in-depth look at your wonderfully educational and passionate site.

    Unfortunately, I was unable to get Idealscope or AGS ASET scope diamond images to get even more reassurance, thus I am turning to you. Is this a good diamond worthwhile of a purchase?
    Thanks for your time!


  29. Paul Gian-
    September 6, 2016 at 1:53 pm

    The stone you picked is quite decent.

    I did a search for you and would recommend these diamonds instead for their better cut quality and light performance:

  30. Alan-
    September 6, 2016 at 3:18 pm

    Dear Paul,

    You are amazing; thank-you so much for giving me your time and consideration.

    I am really getting to appreciate the quality of the cuts you have set out in the two diamonds above. The scope images really seem to affirm this and they look gorgeous (I’m quite partial to the second of the two you listed). Unfortunately I am unable to see the scope images of the original diamond (sku-1806204). Is your assessment of it’s light performance under fluorescent lighting based on experience?

    To be honest, I’m in a situation where I would prefer to go with something that was a straight up IF clarity. Given that is (unfortunately by your standards I know, sorry!) one of the criterion, is there any other diamond that you would recommend in a similar carat category (1.2-1.4)?

    Also, am I being completely unreasonable? I note that for the second diamond (sku-1003601); the cut is better (resulting in better light performance), the carat is larger and the colour is a better grade all for being very slightly cheaper. From your site advice, clarity should be the least important of the 4Cs and is held in higher regard by rookies (of which I am definitely one). Am I being crazy NOT to choose this other diamond?

    My main issue is that if my future wife were to (very) closely examine the second diamond you recommended without the aid of a 10x loupe, would she note these slight inclusions and clouds at all?

    Thanks again for your time Paul :)! I really appreciate it as I want to be absolutely confident in my purchase before going ahead.

    Stay well!

  31. Paul Gian-
    September 7, 2016 at 12:52 am

    The cut precision and performance on the IF diamond isn’t as good as those 2 I recommended. You can see this in the slightly messy black reflections and scintillation under the table. I can assure you that both these diamonds are 100% eyeclean.

  32. Aj H-
    September 28, 2016 at 4:11 pm

    Paul , what is your opinion on strong yellow fluroscence in a diamond ?

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

    It’s great for a fancy color yellow diamond and undesirable in “white” diamonds.

  34. Scott-
    October 4, 2016 at 4:20 am

    Hey Paul,

    FIrst off thanks for running such a great site! My question is one regarding ovals and corresponding Asets.

    Can I tell if either of these two diamonds will have pronounced bowties simply from their Asets. And also which diamond would you prefer at ED?

    SKU: O100-146Z49828
    SKU: O100-595427Z0Z

    Thanks for your input,

  35. Paul Gian-
    October 4, 2016 at 8:25 am

    Static ASET images may be insufficient to detect bowties. You will need to use videos for a better gauge. Based on the listings, I would say that both diamonds display minimal bow ties. Both are well cut and I do prefer this particular diamond: SKU: O105-159059Z25 because of its scintillation pattern.

  36. Torrin-
    October 31, 2016 at 6:12 pm

    Hi Paul –

    I’ve been debating on this diamond for a few days. Thoughts?

  37. mike-
    November 4, 2016 at 6:03 pm

    Would you please explain the different images in the above ASET diamond test comparisons? I’m not sure what I’m looking at. For example, there are 3-4 images per heading (Ave., Above Ave., Ex.) under a given cut shape. Are these 3-4 images the same stone (different angles) or different stones?


  38. Paul Gian-
    November 5, 2016 at 3:01 am

    They are ASET images of different stones. I compiled them in this manner because in reality, no 2 ASET images will look exactly the same. For laymen, you can compare the ASET images of the diamonds you are considering to get an idea of which band it falls into.

  39. Juan-
    December 2, 2016 at 3:19 pm

    Hi Paul,

    Can you give me your opinion on this oval diamond? I have included the imagery (ASET) and Ideal Scope. I am having a lot of trouble interpreting these images for the diamond since it’s a “fancy” shape.

    Shape – Oval Brilliant 8-Main A
    Carat weight – 2.30ct
    Color – D
    Clarity – VS2
    Dimensions – 10.87 x 7.43 x 4.37
    L/W Ratio – 1.46
    Fluorescence – None
    Polish & Symmetry – VG
    Proportions – VG
    Table Diameter – 56%
    Crown Height| – 4.5%
    Pavilion Depth – 41%
    Total Depth – 58.9%
    Girdle Thickness – Thin to slightly thick
    Culet size – pointed
    Certificate – IGI

  40. Paul Gian-
    December 2, 2016 at 4:43 pm

    The diamond isn’t well cut and the ASET shows significant light leakage. The IGI report itself is a huge red flag.

  41. Juan-
    December 2, 2016 at 5:13 pm

    Hi Paul! Thank you for the quick response. For the IGI being a red flag, I have read that GIA is the “gold standard” and IGI tends to over inflate its ratings, hence why people do not trust it. Is that why you say it’s a red flag?

    Also, why do you say it is not well cut? I have read your articles so I want to learn how to recognize a well cut OVAL diamond. Lastly, do you have any examples of good ASET/Idealscope images of ovals? I looked at your reference but can’t really tell the difference between the mediocre and ideal in your post and you didn’t explain what makes one better (again for ovals).

    Thank you and I appreciate all the input!

  42. Paul Gian-
    December 3, 2016 at 5:45 am

    Yes. That’s why IGI is a red flag.

    Basically, you need to take note of the amount of white that occurs in large splotches and how the green/red intermingle with each other. A video of the diamond would be easier to assess cut quality but this diamond already violates quite a number of issues. There’s really no point in further investigation into the stone. Dump it and choose another from GIA.

  43. Tony-
    January 20, 2017 at 5:16 am

    Hi Paul,
    Firstly, thank you for a very informative site which helps demystify a lot of the rubbish that goes on with the retail industry. Can you please let me know your thoughts on this diamond:


  44. Paul Gian-
    January 20, 2017 at 9:20 am

    The stone you picked out is a well cut diamond. Good work!

  45. Brian Kolasa-
    January 23, 2017 at 5:45 pm


    I’ve read all of your articles. You’re the man! Thanks for all of the great info.

    I’m about to pull the trigger on this diamond from James Allen. Based on the video, GIA, and the ASET image they provided, I feel like it’ll be a true sparkler.

    At first glance, could you provide your thoughts on the stone?

    Thank you so much.

  46. Paul Gian-
    January 24, 2017 at 2:56 pm

    Hey Brian, the oval stone you shortlisted has great optical properties (light performance). In terms of shape appeal, I would personally prefer a diamond with a more stubby appearance (i.e. l/w ratio around the 1.3 range). Anyway, that’s up to individual tastes and overall, it’s a good pick.

  47. Heather-
    January 25, 2017 at 11:27 pm

    Hi Paul, would you be able to tell me your thoughts on this oval cut diamond? My main priority is making sure to minimize the bow tie effect that is common with ovals.

  48. Paul Gian-
    January 26, 2017 at 5:49 am

    This is a much better diamond option in terms of cut quality:

  49. Heather-
    February 3, 2017 at 10:48 pm

    Hi Paul, thanks for your suggestion but I prefer a L/W ratio in the range of 1.40-1.45.

    What do you think about this diamond instead?

  50. Paul Gian-
    February 4, 2017 at 12:10 pm

    It’s a very well cut diamond with great optical performance.

  51. Gary-
    July 10, 2017 at 11:10 pm

    Hi Paul

    I was looking to get a second opinion on this diamond as the proportion for the crown/pavillon angle does not fall within the AGS chart for an Ideal cut round diamond. Based on AGS guidelines, the proportions fall more within Very Good to Excellent. So i’m a bit concerned that the light performance(brilliance, sparkle, fire, scintillation, etc) will not be as good as the other Ideal diamonds and more comparable to Very Good/Excellent AGS diamonds.

    This is supposed to be Hearts and Arrow too. What are your thoughts based on the proportions and ASET?


  52. Paul Gian-
    July 12, 2017 at 7:07 am

    Crown angles too low and you will need tangible scope images to determine hearts and arrows precision.

  53. John Calvin-
    July 26, 2017 at 6:55 am

    First off, AMAZING website! But where’s the donate button!? I’d love to be able to donate as a thank you for all this site provides.

    My wife to be was a geology major… so I’m feeling great pressure to pick out a decent stone. Unfortunately I had to pull the trigger quickly because the perfect proposal situation has presented itself and I needed a ring before Aug 7th. James Allen was very helpful and we looked at HUNDREDS of stones together. But I had to buy with out having someone do a physical inspection and ASET photo. Here is the stone he suggested and I did purchase today:

    James Allen is sending me the ASET photos in the next 72 hours. But in the mean time, what do you think? Did the JA representative pick out a good one? He liked that one because he said it looks to have “dramatic sparkle and brilliance”… can he really know that with out seeing it in real life and/or using the ASET diamond test?

    When I propose should I be confident in the stone…. or should we take advantage of their return/exchange policy and pick out something better.

    I’m not after perfection… just that I did a good job.

    Thank you… and again, I’d LOVE to donate!

  54. Daniel-
    November 3, 2017 at 5:16 am

    Hi Paul – really appreciate the website!

    I have a question regarding the ASET image for a cushion cut diamond (2.11 ct). I am working with a smaller independent jeweler and they had to go out to a third party to get the ASET image. Just received it today and was unfortunately not too impressed (center was mostly white while the edges had decent red, blue and some green. I have visually inspected the diamond already and thought it looked good so now I’m a bit lost.

    For the ASET image, I can see the tweezers holding the stone and the image seems not to be taken looking straight down at the stone. Could this be potentially giving the stone a poor color’ing profile?

    Thank you very much for your assistance on this!

  55. Paul Gian-
    November 3, 2017 at 3:43 pm

    Do you have an image or photograph of the ASET?

  56. Dana Ostrovsky-
    November 18, 2017 at 10:23 pm

    I love this site!! Can you please help me with finalizing my choice for a 1.9-2.0 carat cushion cut diamond? The top contenders I have found are:

    Do you have a strong preference for one or two over the other? Any other sites/stones you think I should consider?

  57. Paul Gian-
    November 19, 2017 at 6:54 am

    These both diamonds are the top performers.

    If you want me to assess the ASETs, you can send that via email to me directly. But really, I don’t need the ASETs to tell you that these 2 are phenomenal and will have the best ASET patterning of the lot.

  58. Marc-
    January 29, 2018 at 12:28 am

    Hi, I used one of these after I bought two emerald shape diamonds online, not sure I should say from which site. Anyway the stones where Vg G and but both are almost completely red. But when set in the ring they no longer look like they did. Basically look like glass no real brightness ? Seems like the setting has blocked the light some how. i asked the jeweller who told me that is why he does use gimmicks like this or H&A. Not sure what I should do return the diamonds or check with another jeweller.

  59. Paul Gian-
    January 29, 2018 at 3:27 am

    Do you have an image of the ASET? IF the emerald cut diamond’s appearance CHANGED completely after setting, your setter did a horrible job.

  60. Frank-
    March 9, 2018 at 7:34 pm


    Thank you for all the great info. i have read a lot here and other places and have learnt so much, yet i know there so still so much to learn!

    i want to see what your comments and thoughts are to this statement: “the GIA report and the photo/video of a diamond are much more important than an ASET picture.”

    Thanks in advance,

  61. Paul Gian-
    March 10, 2018 at 2:36 am

    If you are referring to fancy shapes, then yes. With some shapes like oval, marquise, radiant cuts, then the ASET is not as important as videos due to the nature of how light interacts with the diamond. For round cuts or princess cuts, the ASET is IMPORTANT because it can clearly indicate light return.

    March 22, 2018 at 11:02 am

    Paul I am looking to buy a Heart brilliant cut 1.5-2.0 ct to be set as a pendant. I have read your information regarding this style of cut but would like to know (in Order) what are the most important criteria considering it will be worn around the neck and not on the finger. Does that alter how I should approach the choice of the best diamond I can afford?
    I love your website. Ann

  63. Paul Gian-
    March 23, 2018 at 4:21 pm

    Cut quality is essential and for heart shape diamonds, it refers to the sparkle and shape appeal. Next in line would be carat size as you are using it for a necklace.

  64. Paul-
    April 11, 2019 at 4:55 am

    Hi Paul – thank you for the incredibly educational information. As I scramble to decide on a diamond, your resource was super helpful. I’m wondering if I’m able to share with you details about the diamond I’m looking at (I have GIA Report, ASET and “Heart” picture and real picture of the diamond).

    The wholesale dealer in NYC is convinced that this diamond is “best” of its kind in its class (carat, color and clarity), and is convinced that the cut is so incredible that it makes the J diamond look like an H or better. The few inclusions are near one area of the crown edge.

    The trouble is, this was the first diamond I saw so I can’t quite tell if what the dealer is saying is true, and at the time it took some time for me to discern between and G and H color diamonds from this J diamond. I’m really wondering if the cut was so stellar that the color seems whiter. There’s no Fluorescence present.

    Would you be able to help me??

  65. Paul Gian-
    April 11, 2019 at 9:00 am

    Feel free to send me the information you have via email. But based on the ASET alone, I think you should be able to tell whether that jeweler is touting his horn or truthful about his claims. It’s not that hard to tell when you have hard facts for analysis.

  66. Dom-
    May 3, 2019 at 8:39 pm

    Hi Paul
    Thanks for putting this website together, it has been so so useful to me already! I am looking at an oval diamond, with the priority in my search being how sparkly it is. All the information out there seems to suggest that an oval is almost as good as a round diamond in light performance. But looking at the ASET images above, it seems to suggest that the oval cut is one of the worst, if not the worst in light performance? What are your thoughts? Thanks!

  67. Paul Gian-
    May 4, 2019 at 3:21 pm

    Ovals are inherently leaky due to their facet structure and shape. You are right in your observation that ovals are some of the worst performers. They are right there beside the pears when it comes to light return and sparkle. If you want performance, you should buy round diamonds. The reason most people who buy ovals is for their shape appeal.

  68. Mike-
    September 18, 2019 at 5:01 am

    Hi Paul, thank you for providing such detailed and helpful guidance. I received an ASET image from a vendor which appears to be “Above Average – Very Good” according to your ASET reference chart. If you get a chance, can you review the ASET to confirm? Based on your experience, do you have any thoughts on how this diamond would perform?

    Thank you!

  69. Paul Gian-
    September 19, 2019 at 3:51 pm

    It is a decently well cut diamond and would perform perfectly fine!

  70. Michael-
    January 3, 2020 at 10:31 pm

    Oh man, I wish I came across this site sooner! I found a lab grown diamond on James Allen which I was really interested in purchasing but was informed that there was a “bow tie” effect present by a representative. She suggested another lab grown diamond with a slightly less color/clarity grade. By any chance can you help me decipher what diamond would be better? Here are the specs for each of them:

    Diamond 1: The one I originally wanted
    Shape and Cutting Style: Oval Brilliant
    Measurements: 10.27 x 7.53 x 4.31 MM
    Carat Weight 2.14 Carats
    Color Grade: D
    Clarity Grade: Internally Flawless
    Polish: Excellent
    Symmetry: Excellent
    Proportions: ??? (No info on Cert)
    Fluorescence: None

    Diamond 2: Suggested Diamond
    Shape and Cutting Style: Oval Brilliant
    Measurements: 10.02 x 7.27 x 4.58 MM
    Carat Weight 2.11 Carats
    Color Grade: E
    Clarity Grade: VVS 2
    Polish: Excellent
    Symmetry: Excellent
    Proportions: Excellent
    Fluorescence: None

    I even went as far as calculating the crown angle of each of the diamonds as well as the total depth% of the 2nd diamond hoping to obtain an insight as to which one had more of a sparkle and found the following:

    Diamond 1:
    Table Width %: 58.5% (Ideal)
    Crown Angle: %: 32.07 degrees (Very Good)
    Pavilion Depth %: 41% (<Very Good)
    Total Depth %: 57.2% (Excellent)

    Diamond 2:
    Table Width %: 60% (Ideal)
    Crown Angle: %: 35.94 degrees (Ideal)
    Pavilion Depth %: 43.5% (Ideal)
    Total Depth %: 62.999% (Excellent)

    Based on the I.G.I. certificates, it seems that Diamond #1 would have more sparkle, however, based on the information involving I.G.I.'s Cut Grade Parameters it would appear that Diamond #2 has the better cut. Given your expertise, would you be able to tell me which one would "speak to me" more, in other words have more sparkle? Any advice would be greatly appreciated!

  71. Paul Gian-
    January 4, 2020 at 3:05 am

    When it comes to fancy cut diamonds like ovals, any proportion guideline tables are largely useless in giving confirmation of the diamond’s light return. You need to use videos to do that and James Allen’s listings actually have a ton of information to help you analyze the diamonds. I reviewed both diamonds and I can tell you that the 2nd diamond is the much better cut diamond and has better brilliance/scintillation. I would personally buy that diamond over the first one which has a distracting bowtie.

  72. Sam-
    December 14, 2021 at 6:32 am

    It looks like James Allen no longer gives ASET images on request! Bummer

  73. Paul Gian-
    December 15, 2021 at 12:17 pm

    You are right. They stopped that for most of their diamonds after COVID hit.

Leave A Comment