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Diamond Carat Weight

Carat weight (one of the 4C’s) is simply the weight of a diamond, be it one carat or a half carat. It’s all about how much the diamond Weighs.

Back in the days, diamonds were weighed by seeds from a carob tree (where the word carat comes from). These seeds were roughly the weight of one point (1 pt) to a diamond. Since there are 100 points in a full carat diamond, there would be 100 carob seeds to balance it on a scale.

But, as we all know, things grown in nature are never quite perfect (just like diamonds, just like people). Weighing diamonds with seeds was never an exact science.

The Diamond Scale:

Things were never exact until the diamond scale was invented in the early twentieth century. Now, getting the exact carat weight of a diamond is easy and only takes a couple of seconds.

But, no matter how easy it is to find the carat weight, people still have a hard time understanding it.

Decimals, fractions, points, carats, math… can’t they make it anymore difficult?

It all boils down to money.

Carat weights and points are not that hard to comprehend when you know the little secret. Treat carats and points like dollars and pennies. Really! If you can count money, you already know carat weights.

  • One dollar = 100 pennies, right?
  • 25 pennies gives you a quarter, or 1/4 of a dollar.
  • 50 pennies would be 1/2 or 50 cents…

But how do carats fit in?

The same way!

  • There are 100 points in a one carat diamond (written as 1.00 carat). So 1/2 carat diamond would simply be 50 points or .50 carat.
  • A 1/4 carat diamond would be 25 points (.25 carat).
  • 3/4 carat (.75 carat) would be 75 points. Are you following this? It really is that easy.
  • A 10 point diamond is 1/10 of a carat or 10 points.
  • A 1.50 carat diamond is one carat and a half, or a full carat and 50 points (150 points in all).
  • So then when you see a .38 carat diamond, you’ll know it’s a little more than 1/3 carat (.33 CT) and a little less than a half carat (.50 CT).
  • 58 points is in between 1/2 and 3/4 (.50 CT & .75 CT).

So when a jeweler tells you that the center diamond of an engagement ring is 89 points (.89 carat), you’ll know that it’s just 11 points shy of being one full carat (1.00 carat).

Take a look at the image below to see all the different sizes of carat weights.

Carat Weight Chart

Carat Weight Millimeter Sizes

The standard millimeter (mm) sizes of diamond carat weights are as follows:

Standard Diamond Carat Weights

Points – Carats – Fractions

Take a look at the chart below to see what the points are, carats are and fractions are of your diamond. Plus, see what that carat weight is often referred to as.

Diamond Carat Weight Points Carats Fractions Chart

The Dream Carat Weight

If you’ve been looking at diamonds, especially diamond engagement rings, you’ll know that a one carat diamond is the dream diamond. That’s the size that every woman wants (or at least 99.9% of them).

One carat diamonds are the cream of the crop. The show stopper! It’s the perfect size for any diamond ring and the perfect size for any finger.

But sadly, one carat diamonds are large and quite expensive. That’s why the average size for a diamond engagement ring is only 38 pts. So don’t fret it, average works out to be pretty affordable to all. :)

Carat Weight and Carat Weight Total

One thing to note here about carat weights is that there are different types of carat weights that shouldn’t be confused.

If you’re looking at a diamond solitaire (single diamond), then the carat weight is simple; it’s the weight of that one diamond.

But, if you’re looking at a diamond wedding set, then things can change dramatically. You’ll have the carat weight of the center diamond and the carat weight of the side stones.

A lot of times jewelers will give you the carat weight of the entire ring when you’re asking what the carat weight is. They’ll say something like “This is 1.25 carats“. This may sound really good, but when you compare diamond rings elsewhere of 1.25 carats you’ll see that the price is way different… And all for a very good reason…

The jeweler was giving you the total combined carat weight of the entire ring(s)… or carat total weight written as ctw, and not the breakdown of the center diamond and the side stones. This makes a huge difference.

The center diamond could only be .33 carat and the other .92 carat could be in the little side diamonds. That’s not only a big difference in weight, but in looks as well.

The point is, if they give you a carat weight of a ring, make sure you find out if that’s the carat weight of the center diamond or the carat weight of the entire ring. Knowing this info can help you compare rings and prices elsewhere. Otherwise you could easily be taken.

The same carat weights look much different.

Two one carat diamonds put side by side can also look totally different in size as well. It’s like two people standing side by side could be the same weight, but one could be tall and skinny, the other short and fat. Diamonds are no different. From the top view, one could look 25% smaller than the other diamond, if not more. It all depends on how the diamond is cut (which all depends on how much profit they can make from the initial parent rock).

In carat weights, you have to look at everything to understand what’s really going on. Things like mm sizes, ideal proportions and girdle thickness all come into play (which we will all get into with other posts).

Everything is affected by carat weight, even the inclusions in the stone (or more appropriately, the clarity of the diamond). Carat weight affects how strictly diamonds are graded as well. Bigger diamonds get graded more thoroughly.

Larger carat weights make it easier to spot flaws and imperfections, plus larger carat weights also show off the color of the diamond easier.

All good things to consider with carat weights…

(Which includes the “dream carat weight” diamonds HERE!)

We will get to all this, but for now, it’s time for the next C of the 4C’s:

Diamond 4Cs Guide Diamond 4Cs Cut Guide Diamond 4Cs Color Guide Diamond 4Cs Clarity Guide


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  1. Thank you that was so help full

  2. Thank you you taught me few things I did not know before

  3. I have a 10 point diamond sitting inside a 18 ct gold ring
    Just need to know what it’s closest worth us to sell it
    And one valuer said it was just below there threshold to buy it
    I’m confused as to what that means if u know pls tell me

    • Hi Lamiya. I can’t tell you from the information you supplied. You would have to get a value from someone who could physically look at the ring, the quality of the stone, measure it, get the weight of the gold, the condition… All to get some kind of a value, which is usually about 20-30% of what you paid for it. -Richard

  4. Annika Zajac // January 22, 2017 at 3:39 pm // Reply

    My fiancé and I are currently looking for an engagement ring and found what we wanted but are waiting for the jeweller to find the right diamond for us.
    I did my research properly about The 4 C but yet I found when we were a shops some jewellers trying to pursuade me to go down in clarity to SI we don’t want.
    We have now requested the following:
    Solitaire Diamond:
    Carat: 0.50
    Colour: D-F and possibly a G (GIA chart/certificate)
    Cut: Excellent
    Clarity: VV2-VS1

    Is there anything else I should think of? I am aware that the cut is important but it is to do also with how wide it is as well as thick?
    Please give me some advice as I noticed that SEVERAL of the jeweller shops and especially in Hatton Gardens in London give you a lot of the sales talk and even if we did our research they talked to us as if we did not know what we were talking about.
    Some jewellers think that all you as a woman seek is a massive size and a massive spark. In my opinion I rather go down in size then having lower quality on the clarity as SI. I have several friends wearing diamond where you see infusions or where the light isn’t reflecting properly.
    So…as an outsider can you advise me if I am thinking right or wrong. Would you for example go down to a VS1 and than increase the Colour to D,E instead of F? And what do you think of a G colour? I don’t want to be ripped off here.
    Advice advice please . Thanks Annika

    • Hi Annika. What you are looking for will be a stunning diamond. Anything in the VVS range, with a Pure White Color will be beautiful. Especially with an Excellent Cut. You can go down to a VS range (VS1 or 2) and visibly, it would look identical (only slight differences under a microscope), so that will save you some money. And don’t worry about the carat weight, the average stone size for an engagement ring is just .38 points. And, if you look at stones just a couple of points shy (like 48 points) it WILL knock the price down hundreds of dollars. :) And you can always upgrade the carat weight later on down the line, like a 10th anniversary or something. :)
      I would look online with James Allen:

        .48 VVS1-2, D-E-F, Excellent Round Diamonds

      As well as:

        .48 VS1-2, D-E-F, Excellent Round Diamonds

      You’ll save a lot of money, and get a stunning GIA certified diamond, that you can see inside the stone, right now!

      Good luck, and congrats! :)

  5. Annika Zajac // January 22, 2017 at 3:43 pm // Reply

    One more question. Is the value effected if it is an uneven number in carat? What I mean is it valued as I’m not really perfect? For example 0.51 instead of 0.50? Sometimes on certain websites it can be cheaper to get a 0.51 instead of 0.50. Just interested to understand how it works.

  6. Hi! I have a watch that is 90 diamonds – and it’s supposed to be a combined weight of 2/5 ct. – will a diamond tester be able to verify if it’s real by testing just one of those diamonds or is that too small to be able to show up on a diamond tester pen?

    • As long as there is enough table for the tester to rest on, you should be able to test them. Small diamonds can be tricky and difficult, but usually with patience you can get an accurate reading. -Richard

  7. Angelia Hall // December 17, 2019 at 6:27 pm // Reply

    How do you tell about champagne diamonds? The color, clarity? I have a diamonds bracelet that has 28 diamonds, 2 have been replaced with 4 point lighter diamonds but the other 26 are 4 point beautifuly matched champagne diamonds set in 14k yellow gd.

  8. In the description of the diamond ring there is inclusion:
    counts: 21 – 50

    What does it mean?

  9. I have a watch that has and this is straight off the back. It says 0.60 CT TW-108 DIAMONDS, so it would be a tenth over a 1/2 karat, rite?

  10. Kathleen Garone // November 24, 2020 at 9:45 pm // Reply

    My engagement ring purchased in Tiffany’s in New York is 60 points and is a flawless stone. What word describes its perfection?


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