What you need to know

  • “Carat” is the term used to refer to the weight of a diamond (not to be confused with the term “karat” referring the purity of gold)
  • Carat is the weight of a diamond and by its self does not necessarily reflect its size.
  • We tend to evaluate diamond size by viewing it from the top because that is how diamonds are most commonly seen when set into a ring.
  • To gain an accurate understanding of diamond size, carat weight should be considered in conjunction with two other key aspects:

– Distance in millimetres across the top of the diamond, as this will vary based on the diamond shape – see Diamond size chart below

– Diamond’s cut grade




carat-chart-buttonThis document illustrates how carat weight and shape will determine how a diamond looks when viewed from above. This document is for guide purposes only, your actual diamond may differ in terms of length / width ratio, table and depth.


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The term carat weight, specifically refers to the weight of the diamond, however it is important not to confuse carat weight with size, as there are other aspects of a diamond that can affect how large it actually appears.

To gain a precise understanding of diamond size, Lover’s Rock recommends considering carat weight with two other key aspects:

1) The distance across the top of the diamond measured in millimetres, as this will vary based on the diamond shape

It is important to measure the distance across the top of the diamond as this is how we view a stone when set into a ring. Likewise, your chosen diamond shape can have an effect, as for example elongated shapes (Marquise or Oval) tend to maximise carat weight, making them appear larger than rounded stones of the same weight.

2) The diamond’s cut grade.

A diamond’s cut grade should also be considered because, as we noted in the cut grade section, when a diamond is cut with the proper proportions, the maximum amount of light (brilliance or sparkle) reflects back out of the top of the diamond. When a diamond is well cut, the light reflected out of the top makes it appear larger. In a poorly cut diamond, light entering the diamond ‘leaks’ out from the bottom (if cut too shallow) or sides (if cut too deep), producing poorer light reflection and therefore less brilliance or sparkle, making the diamond appear smaller than its carat weight would imply.

It is therefore possible to have a diamond of a lower carat weight, but higher cut grade, which appears larger than a diamond with a larger carat weight, but poor cut.

Carat Weight

  • Carat is measured in cts or points.
  • One-carat is divided into 100 points. Therefore, 0.50cts is equivalent to 50 points, 0.25 to 25 points and so on

Which Carat Weight Is Best for My Budget?

To choose the best carat weight of diamond, consider the size of her finger, the size of your ring setting, and your budget.

  • In order to define your budget, we at Lover’s Rock recommend first selecting your cut, colour, and clarity grades, to determine the carat weight of diamond that will fit within your budget.
  • If a large carat weight is important to you, yet you’re working within a strict budget, consider a diamond with a good cut, SI1-SI2 clarity, and an I or J colour grade.
  • Diamond prices significantly increase at the full- and half-carat weights. Diamonds just below these weights cost significantly less, and, because carat weight is distributed across the entirety of the diamond, small size differences are almost impossible to detect.
  • Consider the size of the wearer’s finger. The smaller the finger, the larger the diamond will appear.

Now that you understand carat weight, learn about a diamond’s cut.

Have a question?

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