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Importance of Carats for Diamond Lovers

Importance of Carats for Diamond Lovers

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Importance of Carats for Diamond Lovers

Nearly every consumer, whether they know much about jewelry or not, has heard the term "carat" associated with diamonds. But not even all diamond lovers know what it means other than higher numbers are usually worth more. The following information will help demystify what carats are and why they matter in diamond valuation.

Measuring Diamond Weight

Carats measure diamond weight, which is important because the heavier the stone, the more likely it commands more value. Over a century ago, industry leaders set 1 carat at 200 milligrams as a reference for measuring diamond weight. Carat weight is usually more critical to value than diamond size, but sometimes there are exceptions when the shape is unique. Size is also important for measuring a diamond ring's setting.

It's possible to generally compare size and weight for certain round diamonds using a jewelry industry diamond chart. A typical 2 ct. round diamond often has a diameter of about 8.1 mm, which is a little less than half the diameter of a U.S. dime. A 3 ct. diamond often coincides with a diameter of 9.1 mm, which has about the same width as a fingernail.

Glossary of Terms Related To Carats

  • Ct: Abbreviation for carat.
  • Diamond size: Measurement of a diamond's diameter in millimeters.
  • Length-to-width ratio: This figure helps gemologists calculate diamond shape if it isn't round.
  • Points: Jewelers use a point system in which 1 carat is equivalent to 100 points, whereas 2 carats = 200 points.
  • Pointers: The size in millimeters can be expressed as a pointer, such as a 1-pointer is equivalent to a .01 carat diamond.
  • Total carat weight (TCW): This measurement combines all items in a diamond-based jewel, such as a diamond, the metal ring, and other types of gems.

How Carats Affect Diamond Value

One of the most common misconceptions about diamonds is that carat weight always matters the most. In some cases, weight can be the most crucial factor in pricing, but for the most part, it's merely one of the 4C's. The other three C's (cut, color, and clarity) are often overriding factors for gemologists in determining fair market value of a diamond. The cut is sometimes more significant to an appraiser because of the skill that went into crafting a unique jewel.

Another common misconception is that many people assume the bigger a diamond looks, the heavier its weight will be. But size and weight do not correspond proportionally. To be clear, a 2 carat diamond is not twice the size of a 1 carat diamond.

You can look at a professional diamond chart displaying images of gem sizes in millimeters matched with weight in carats to get a good idea on the relationship between diamond size and weight. But when shape, length, and width are very unique, a diamond chart won't be effective for matching weight with size.

Heavier carat weights often correspond with higher value if cut, color, and clarity also get high grades. Carat weight becomes less important to overall value if the quality of the gem is degraded in some way. Conversely, it can strengthen value when all other factors are positive.


Learning about the significance of carat weight is essential in understanding how diamonds are valued. The more you associate with jewelry experts, the more your knowledge base will grow, helping you find the best deals. Contact Ralph Mueller & Associates for more information on evaluating diamonds. We can help you sell your jewels or buy from the diverse global market.