The Size Comparison Between MM and Carat Weight for Lab diamond engagement rings


When shopping for a lab diamond engagement rings, it’s important to understand the size comparison between mm and carat weight. Carat weight is a measure of a diamond’s mass, while mm is a measure of its diameter. A diamond’s size will depend on both its carat weight and its cut.

Carat Weight

One carat is equal to 200 milligrams. A diamond’s carat weight is determined by its mass. The larger the diamond, the more carats it will weigh. However, carat weight is not the only factor that determines a diamond’s size. The cut of the diamond also plays

  • Cut

The cut of a diamond refers to the way it is faceted. The cut of a diamond affects its size, shape, and sparkle. A well-cut diamond will appear larger than a poorly cut diamond of the same carat weight.

MM Size

The mm size of a diamond refers to its diameter. The diameter of a diamond is measured from one point to the opposite point across the widest part of the diamond. The mm size of a diamond will vary depending on its carat weight and cut.

Size Comparison

The size comparison between mm and carat weight can be confusing. A general rule of thumb is that a 1-carat diamond will be about 6.5 mm in diameter. However, this size can vary depending on the cut of the diamond. For example, a round brilliant cut diamond will be slightly larger than a princess cut diamond of the same carat weight.

Here is a table of size comparisons for different carat weights and cuts of lab diamonds:

Carat Round Brilliant Princess
Weight Cut Cut


0.25                            4.1 mm                                  3.7 mm

0.50                            5.2 mm                                  4.7 mm

1.00                            6.5 mm                                  5.9 mm

1.50                            7.8 mm                                  7.1 mm

2.00                            8.1 mm                                  7.4 mm


The size comparison between mm and carat weight is important to understand when shopping for a lab diamond engagement ring. By understanding this comparison, you can better visualize the size of the diamond you are considering. You can also use this information to compare different diamonds and find the one that is the right size for you.

Here are some additional tips for choosing the right size lab diamond engagement ring:

  • Consider the size of your finger. The larger your finger, the larger the diamond you can wear comfortably.
  • Think about the style of the ring. Some ring styles, such as solitaire rings, will make the diamond appear larger than others, such as halo rings.
  • Ask to see the diamond in person. This will give you a better idea of its size and how it looks on your finger.

With a little research, you can find the perfect lab diamond engagement ring for your budget and style.

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