When Would I Notice Size Differences in Carat Weights?

layout of different types of diamond shapes

What carat size should I choose? Would I be able to notice a difference between 2 diamonds that are 0.3 mm apart? When would I start noticing visual size differences with diamonds from various carat weight brackets?

If you are one of the people with these questions in mind, don’t worry, you aren’t alone. In fact, I get asked questions like these frequently via emails and decided to create this blog post to answer them.

First things first, let’s address why people ask these questions.

Since we are talking about an engagement ring that probably costs thousands of dollars, I can tell you that the fundamental reason is always related to cost. After all, who doesn’t want to make a purchasing decision that gets you the best value for money.

Diamond Prices Have an Exponential Relationship With Carat Weight

Diamond prices jump at every 10 points (0.1 carat). For example, a 0.50 carat diamond would cost about 30% more than a 0.40 carat diamond with similar specifications.

Yet, the real difference in size between these 2 stones is roughly 0.4mm. And if you pick up a ruler and look at the subdivisions, a 0.4mm difference might not be that big of a size difference.

how does 1 mm look like

Ruler showing 1mm markings

To help with visualization of different sizes, I’ve compiled a printable chart of real-life diamond sizes and their relative carat weights. Click here to check it out and download a copy in .pdf format.

The Key Question Is: Can You Tell The Differences?

Weird as it seems, people tend to notice the 0.4mm difference when comparing objects of smaller sizes. When comparing bigger objects, our brains seem to perceive the same difference as insignificant.

Let me show you some examples to illustrate this…

size difference between .4 carat and .5 carat4.8mm vs 5.2mm

Do you see the difference of 0.4mm between the 2 circles above? Well, most people do notice this subtle difference when they compare a 0.40 carat diamond against a 0.50 carat diamond.

size difference between 1.50carat and 1.75 carat

7.4mm vs 7.8mm

In contrast, the same physical difference of 0.4mm between a 1.50 carat diamond and 1.75 carat diamond isn’t readily detected because of the way our brain works.

If you want to get a high quality engagement ring and better value for your money, I highly recommend vendors like James Allen, Whiteflash and Brian Gavin where you can visually see exactly how the diamond looks like.

Here Are a Few Other Examples to Check Out…

can you tell the size difference between 0.9 carat and 1.0 carat

6.2mm vs 6.5mm

Also, what happens if I place the diamonds further away from each other?


further apart



comparison at a distance


Do you realize it is harder to notice size difference now? In real life, most people casually observe diamonds from a distance and it isn’t easy for them to pick up minute differences.

Now, for people who intend to buy diamonds within the 0.50 – 0.75 carat ranges, I performed another comparison to help you visualize how they would look like in reality. If you refer to the image below, I think it is pretty clear that you would notice an obvious size difference.

size difference between carats of 0.50 and 0.755.2 mm – 5.8mm

Ultimately, Your Opinion Is What Matters Most!

So, what do you think?

Perception is more of a subjective matter than an objective one. Some people see differences in sizes easily and some don’t. It is the same with diamond color where some individuals can see clear differences between F and G color diamonds whereas the majority of us don’t.

I know of people who are psychologically affected by the size of the diamond in their minds. Even if they are wearing a 0.92 carat diamond, in their mind, it is never good enough unless it is a 1 carat diamond.

At the end of the day, go for a carat size that’s “mind-clean” and affordable to your wallet. After all, diamonds are purchases which are meant to be enjoyed instead of being something that constantly frets you at the back of your mind.

If you are looking for a diamond that is cut to the best standards and optimal light performance, I recommend checking out Whiteflash and Brian Gavin. Their signature diamonds look spectacular in real life and represent the top 1% of well-cut diamonds in the market.

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  1. teresa-
    August 25, 2012 at 2:13 am

    what would be a fair price for a diamond with 0.53 carats, F color and VS2 clarity?

  2. Paul-
    August 25, 2012 at 9:18 am

    Unfortunately there is no way to tell with the limited information that you had posted.

    If possible, please include the shape of the stone and grading report in order for me to give you accurate advice.


  3. Ludmila Pechalová-
    September 14, 2012 at 5:01 am

    I am actually considering a split shank design for my new ring project. Are there any tips or advice that you would offer for one that would enhance the size of the center stone?

  4. Paul-
    September 16, 2012 at 10:32 am

    A halo setting would help greatly when done right.

    I had made a blog post on how different ring designs can help enhance the physical size of the center stone. It’s well worth your time checking it out here:


  5. Nicoline J. Karlsen-
    October 4, 2012 at 1:03 am

    Does this look like a good buy?

    Pear: 1.21 carat, 62% depth, 59% table, F color and VVS2 clarity.

    Thanks for the awesome website and your opinion on this stone…

  6. Paul-
    October 5, 2012 at 11:43 am

    Hi Nicoline,

    On paper, it seems like an OK choice. However, I won’t recommend buying a pear shaped based purely on paper. There are some aspects like bowties and light performance factors that a grading report won’t tell you.

    Please read the following links for more details:


    Feel free to bump me an email if you have further questions.

  7. Stephen-
    October 8, 2016 at 12:11 pm

    Hi would you go for a .40 round brilliant Colour F Internaly flawless cut excellent or
    .50 colour H VS1 very good cut ??

  8. Paul Gian-
    October 8, 2016 at 2:56 pm

    Neither. The flawless clarity is a waste of money. The very good cut on the H diamond is just a turn off.

  9. Michelle-
    December 23, 2016 at 10:06 pm

    Hi Paul,
    I’m glad I found your site. Just curious regarding your answer to ” Hi would you go for a .40 round brilliant Colour F Internaly flawless cut excellent or .50 colour H VS1 very good cut ??”. Why do you say ” flawless clarity is a waste of money” ?

    I m considering buying an round, F, IF, excellent cut/ symmetry/ polish.

  10. Paul Gian-
    December 26, 2016 at 3:44 pm

    In reality, you won’t be able to see differences with the naked eyes between a VS diamond and an IF diamond. That’s why I think it is a waste of money unless you are looking for symbolic reasons for an internally flawless stone.

  11. cherri gibson-
    March 30, 2017 at 2:08 pm

    Hi there, i am looking at a tiffany. Vs1 and h in colour. All papers say excellent cut. It is platinum. But the stone is a tiny .21 on my large fingers. The seller wants £500! What do you think?

  12. Paul Gian-
    March 31, 2017 at 12:23 am

    This deal sounds dodgy to me because a real and original platinum setting from Tiffany & Co would cost more than £500. If the vendor has the original certificate and can prove that it is an authentic Tiffany ring, I think it is a decent buy. As for the diamond being small for your fingers, I’m not sure what kind of carat sizes you are expecting here. Are you expecting to get anything larger than 0.2 carats realistically with that budget range?

  13. Romayne-
    April 7, 2017 at 4:08 pm

    Hi Paul, Took your advice and checked out James Allen, love it! On the GIA reports, what refers to the cut? Is it the polish/symmetry characteristic? Is it better to have a higher grade on the polish or the symmetry or do both go together and should be excellent all around?

  14. Paul Gian-
    April 8, 2017 at 1:57 am

    Depends on the shape of diamond you are looking for. If you are looking for round brilliants, polish and symmetry would be important factors to keep at excellent ratings. For fancy shape diamonds, they aren’t necessarily that crucial and you will need other information such as videos/ASETs to help you determine cut quality.

  15. Jerring-
    September 12, 2017 at 8:35 am

    Hi Paul,

    Is it worth to buy a 0.31 GIA certified internally flawless Ex Ex Ex cut grade in f colour or should I buy a bigger size with a bit less of the quality?


  16. Paul Gian-
    September 12, 2017 at 8:56 am

    Ask yourself, why do you need the IF clarity for? If you need it for symbolic reasons, by all means get the stone. Otherwise, you are just throwing your money away into an aspect that your eyes cannot appreciate.

  17. Brett-
    September 13, 2017 at 2:18 pm

    Hello Paul, I’m currently looking to buy a emerald cut diamond. If it wasn’t emerald cut I wouldn’t be as concerned with the clarity and color. Currently I am looking at VVS1 or higher, G or higher. Am I wasting money when I could go lower because all I’m concerned about is how it looks through the naked eye.

  18. Paul Gian-
    September 13, 2017 at 4:26 pm

    Depends on what carat size you are looking to buy. I would say that VS1s would be more than enough to ensure eyecleanliness.

  19. Keith-
    November 27, 2017 at 1:19 pm

    Hi Paul, I was thinking of buying a Cartier 1895 paved round dimond ring platinum, carat . 4ct Colour h, vs1 .. Price 4350 uk pounds do you consider that as best value for that type of ring?

  20. Paul Gian-
    November 28, 2017 at 2:21 am

    Putting value with branded goods is kind of an oxymoron. For such a small sized diamond ring and priced excessively at 4350 pounds, you can get a better cut diamond and setting at a quarter of those prices.


  21. lynn-
    January 5, 2018 at 12:40 am

    I would really like your advice, I am purchasing an eternity band. I am not sure if I should go with .40 f sl1 or go with .45 diamonds sl1. which one would have more spark.. Any advise is welcome ty Lynn

  22. Paul Gian-
    January 5, 2018 at 3:13 am

    Size is not the determining factor of whether a diamond will sparkle or not. Cut quality is. If you are looking for the best sparkle in an eternity ring, go to Brian Gavin or White Flash. They use super ideal cut diamonds for their melee stones.

  23. Jenan-
    February 10, 2018 at 1:47 am

    Hi there!

    We’re looking at one diamond that is VS2, round brilliant, 1.36 I and VS2 round brilliant, 1.46 J. These are comparably priced, and although I like the 1.46 size, the J color turns me off since I’m color sensitive (even though the cut is gorgeous).

    The alternative is VS2 round brilliant 1.54 G for around $2000 more. Is this good value? Or do you think there isn’t a big difference between 1.36 and 1.46 size if I’m satisfied with an I color?

  24. Paul Gian-
    February 10, 2018 at 4:35 am

    The ct weight differences will not be obvious ASSUMING these diamonds have identical cut quality (which I doubt so).

  25. Kelly McCormack-
    March 21, 2018 at 4:48 pm

    Hello Paul,
    First off I’ve read nearly every page and everything you’ve wrote, so please don’t judge me – I already took your advice and own a “real” diamond!
    I’m thinking of taking a leap and buying this on line from an established estate seller. (I know I know) However if I don’t like it I can return it, no questions asked and for the full amount – so it’s like ordering clothes on line – try on, if it doesn’t work, return it….
    It’s a .91CT Old Miner cut center diamond VS2 clarity/I color. It’s set in platinum with 2, .02 side diamonds of the same quality.
    So, a couple of questions:
    1. What is an old miner cut? I’ve read a few things about it, but the cut alone sounds like the guy who dug the diamond out of the earth, sat there in the mine and hand cut it!
    2. Are you a fan of the old cut diamonds? I understand they were hand cut (and no two alike) vs machine cut, but they hold a type of romance for me.
    3. Then there’s the Old European Cut. What’s the difference?
    4. I also understand the rules about cut being the most important, but that’s all the info I have.
    5. It’s $850 USD, which would be my birthday gift, but should I? Or get something else for the money? I love unique things.
    Thanks for listening to all my rambling!
    I look forward to your reply.

  26. Paul Gian-
    March 21, 2018 at 5:49 pm

    Let me provide some honest feedback and tips on things to look out for. First of all, who graded the diamond? GIA or some other unreliable lab?

    1) https://beyond4cs.com/shapes/cushion/old-mine-cut/

    2) I’m not a fan of old cut diamonds as I prefer the modern looks. Well, you are wrong about “machine cutting”. In the market, the better diamonds are cut and polished by hand.

    3) https://beyond4cs.com/shapes/round/old-european-cut/ The differences lie mainly in shape and outline.

    4) https://beyond4cs.com/diamond-certification-mistakes-to-avoid/

    5) It’s really up to you to spend your money but I can tell you that for this amount of budget, the 0.91ct diamond is definitely misrepresented. It’s not going to be an I/VS2 for sure. So, you are going to get ripped off in this purchase. And I already have an answer to the question I posed. GIA definitely didn’t grade this diamond. If the stone’s qualities are accurately represented, there’s no way it is priced like this.

  27. Adam-
    March 25, 2018 at 2:41 am

    Hi Paul,
    I’m new here but this is a great site. Quick one…

    Princess cut: 1.2ct / G / VS1 / Excellent polish / G symmetry vs
    1.1ct / D / VS2 / VG polish / G symmetry

    The 1.2ct is priced $950 higher. Those specs above i would have thought the smaller ct would be more. Both options ive found online. Is the difference just bc the ct weight is higher? If so, are either of those spec differences visible to the naked eye?

  28. Paul Gian-
    March 25, 2018 at 5:13 pm

    You would want to read every single word here:

    Buying Diamonds Blind (It’s Plain Dumb) Or Based On a Grading Report? https://beyond4cs.com/buying-diamonds-blind/

  29. Elsie-
    June 2, 2018 at 11:57 am

    I am trying to tell the differences between a .8 carat vs 1 carat cushion diamond. How do you account for girdle thickness variations if one is cut with an extremely thick girdle while the other is cut with a thin girdle?

  30. Paul Gian-
    June 4, 2018 at 7:12 am

    I don’t account for girdle variations since every single fancy shape stone can be polished in a unique manner. Let me ask you: can you tell the difference between .9 carat and 1 carat? If you can, you can definitely see the differences between a 0.80 carat vs 1 carat cushion.

    Here’s something else you can do as well. Refer to the grading reports for the corresponding dimensions of the 2 stones. Take a blank piece of paper and sketch the outline in a similar way that I did the tests above.

  31. Lindsey Hintz-
    August 31, 2019 at 2:23 am

    Hi there,

    Not sure if you’re still active on this thread but I’ll ask anyway. I currently have round brilliant .45 carat H SI2 diamond and am considering trading it in for an upgrade. The jeweler said he’d give me $800 for mine and would sell me a couple of options. A modern ideal .54 F S1 for $2150, a .68 carat H SI1 for $2700, .66 carat D S1 or 2 for $2385 or a .92 D S1 or 2 for $4500. I’m wondering if any of these are good deals or am I paying way too much and should look elsewhere? Or should I just keep the original stone and put it in a different setting? What would you recommend?

  32. Paul Gian-
    August 31, 2019 at 3:15 am

    It would depend on details. First of all, cut quality matters and I don’t have tangible data on each of these diamonds to make any constructive comments. Secondly, who graded all the diamonds? I would expect nothing less than GIA or AGS for all the stated diamonds that the seller is offering. With all these details would you only be able to make any price comparisons properly and justify whether they are worth it for their costs.

    Read these too:

  33. Lance Liberstein-
    October 28, 2019 at 4:34 am

    Hi Paul,

    Question, I am currently in the market for a custom mens 14k yellow gold diamond wedding band.

    After, speaking with Blue Nile, James Allen, and 2 local jewelers, I decided to go with whiteflash.

    The custom wedding band will be comprised of (5 diamonds set in a line).

    My conflict:

    ***All these diamonds are whiteflash’s top of the line ideal cut “A Cut Above” AGS triple 0 loose diamonds.

    (5) .30ct (30 points) J color, S1-VS1, A Cut Above” at $2900 for all 5.


    (5) .40ct (40 points) F Color, S1-VS1, A Cut Above at $6,000 for all 5.

    Those prices are independent of $1,500 for the ring and labor.

    My worries: It may be too small in diamond “size” vs the 40 point diamonds. and the possible yellowish tint.

    1. Is their a significant difference from 30 to 40 points in terms of size or perceived size?
    2. Would there be a noticeable difference in color from J to F in a yellow gold setting?

    I dont want to pay double in price to get 33% more in carat weight, if not a major noticeable difference.

    Thanks for any feedback.

  34. Paul Gian-
    October 28, 2019 at 4:08 pm

    Color is subjective and the perception of color would vary from one person to another. You should watch this video that compares F vs H vs K diamonds: https://www.youtube.com/watch?v=lqlGfACJwPA

    I would say that at this carat size, it would be hard to pick up color nuances. However, there will be a noticeable difference between 0.3 and 0.4ct diamonds. If you were buying a platinum ring, then going for the set of 5 F diamonds would make sense. For a yellow gold setting, going to a set of 5 Is or Js would be perfectly fine.

    In my opinion, color should be the least of your worries. Carat size comes as a bigger priority over color.

    I did a search for you and alternatively, you can also consider something middle ground like this:


    This mixture of H & I diamonds would also look great and will face up white (although anything placed in a yellow metal setting would make it appear yellowish). More importantly, it will give you the bigger size you are looking for.

  35. James-
    January 3, 2022 at 10:01 am

    Hi Paul

    I’m buying a 2.86 E vvs radiant but concerns that a 3ct Vs G will look drastically larger . After reading I feel the color will be basically the same . Thoughts?

  36. Paul Gian-
    January 10, 2022 at 9:22 am

    If the diamond is graded by GIA, it is likely that you will not notice color differences in both diamonds. For radiant cut diamonds, the physical size of the diamond can vary greatly depending on how it was cut (i.e. high depth percentages or high length to width ratios). A 3ct diamond doesn’t necessarily look bigger than a 2.86ct diamond. Carat weight itself doesn’t tell you much except for how heavy the stones are. Look at the dimensions in the grading report and that will give you a clearer idea of how their physical size stacks up.

  37. Kristie-
    February 5, 2023 at 4:51 pm

    Love your posting about “mm” differences. Have been driving myself insane over a 5 carat oval that is .47mm shorter than the other 5 carat. Your explanation helped me realize it’s more in my head. Curious what you would think about the prices I got!?

  38. Paul Gian-
    February 21, 2023 at 5:20 pm

    It’s not that easy to valuate 5 carat diamonds because every single detail will have quite a big impact on price. For example, a single higher grade from VS1 to VVS2 can affect prices. A diamond with better cut precision can also affect prices by quite a bit.

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