Carat Weight

When people talk about how “big” a diamond is, they’re referring to its Carat Weight.  Of the 4C’s, carat weight is definitely the least understood.  Having a good grasp of what “carats” actually refer to will help you better navigate the diamond shopping process.

Our Money Saving Tips and Recommendations

  • Carats refers to weight, not size
  • Set your budget first.  This will help you determine how large a diamond (in carat weight) you should purchase.
  • Look for an ideal cut grade.  This will help your diamond look larger without spending on extra carat weight
  • Buy a stone just under 0.5 carats or 1.0 carats to avoid the price jump
  • Consider a halo setting.  A small center diamond surrounded by smaller accent diamonds makes for a large look

What Exactly is Carat Weight?

People often think “carats” refers to the size of the diamond – in other words, how big the diamond looks in millimeters (mm).  In actuality, “carats” refers to the weight of the diamond itself.  Carats uses a measure of mass called “points”, where 1 point is 1/100th of a carat.  So:

  • 100 points = 1 carat = 0.2 grams

Diamonds are like Icebergs: They Hide their Weight

To understand the misconceptions around carat weight, it’s important to remember that when most people look at a diamond, they look at it from a bird’s eye view because the diamond is already in a setting.  As such, they see only the top face of the stone and incorrectly associate its size (width in mm) with the carat value of the stone.


Similar to viewing an iceberg from a plane above, a birds-eye view of a diamond hides two (2) important aspects:

    1. The height (depth) of a diamond
    2. The amount of mass below the widest part of the diamond (i.e. the portion of the iceberg below the water)

The combination of these two aspects defines how the weight of the diamond is distributed.

How Carat Weight and Cut Affect a Diamonds Size

Assuming you had a 1.0 carat diamond, when viewed from above the visible size of the diamond (mm from edge to edge) would be different based on the cut of the diamond.  In the illustration below, all the diamonds share the same carat weight (1.0 carat) but are cut differently.  The shallow cut diamond has a large “spread” and looks bigger but leaks light.   The deep cut diamond has a smaller spread and looks smaller.

Shallow Cut

Ideal Cut

Deep Cut


How do I Select a Carat Weight?

The carat weight you’re shopping for is usually influenced by a few factors, the most important being your budget.  If you’ve had conversations with your loved one about their ideal diamond, then their preferences will also come into play.

When determining what carat weight you are ultimately looking for, use the following tips and tricks to get the most out of your budget.

  • Start with the best cut grade that you can afford.  An ideal cut grade will maximize light return and will make a diamond look larger than it’s true carat weight.
  • There is a price jump at the 0.50-carat and 1.0-carat weight.  Consider getting something just under those thresholds (0.49 and 0.99 carat weight) to get the most for your money. The 0.01 is unnoticeable.
  • Consider a setting with smaller diamonds around a central diamond.  The advantage of this is you can go with a smaller central diamond while creating an overall look / feel of a larger diamond.
carat weight scale, diamond sizing chart

In order to help you answer the ever important question of “how big of a diamond should I buy”, the above chart gives you an idea of the average width of an ideal cut diamond based on its carat weight.  This should serve as a guide as the size (in mm) will vary slightly.  For example, a well cut 1.0 carat diamond is typically 6.5mm but you can expect to see +/- 0.2mm variations.  Use this guide in combination with your budget to start your search.

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