Diamond Carat Calculator

Diamond carat weight has a big impact on the value of your diamond. So whether you are looking to find out the carat weight of your diamond to better understand its worth or simply out of curiosity, myGemma is here to help.

diamond carat weight calculator

A quick and easy options for calculating carat weight:

But what exactly is carat weight and why is it so important? Our gemologists answer the following common diamond carat weight questions:

  1. What is carat weight?
  2. What is the difference between carat weight and diamond size?
  3. How is carat weight calculated?
  4. How does carat weight affect a diamond’s value?
  5. When do I need to use a diamond carat calculator?
  6. Are online diamond carat calculators accurate?
  7. Can I get a price for my diamond based on carat weight alone?


how to calculate diamond weight


1. What Is Carat Weight?

Carat weight, abbreviated to ct, is the unit of measurement used to establish the weight of a diamond. It is arguably the characteristic that has the biggest impact on the price of a diamond.

The term “carat” stretches back to ancient times when carob seeds were used as a unit of measurement thanks to their consistent weight of 0.20g.

Often confused with size, carat weight does obviously affect how large a diamond looks but that it is not what it is measuring. Another important distinction to make is the difference between carat and karat. Carat refers to gemstone weight whereas karat refers to gold purity.

2. What Is The Difference Between Weight And Diamond Size?

To put it simply, carat refers to the weight of a diamond while size refers to how large or small your stone appears. Along with carat weight, the shape and proportions of the diamond also affect how large a diamond looks. A common example of this is that a round cut diamond of 1ct will often look smaller than an oval cut diamond of 1ct. Why? Because an oval cut has a larger surface area.


3. How Is Carat Weight Calculated?

To calculate the carat weight of a diamond, a gemologist will weigh the stone using highly accurate diamond scales. Carat weight is measured to the thousandth of a carat and rounded to the nearest one hundredth.

Should you choose to calculate your diamonds carat weight yourself, you have 2 options:

  1. Weigh the diamond in grams and divide it by 0.2. For example, if your diamond weighs 0.2 grams, dividing this by 0.2 means that you diamond weighs 1ct.
  2. Print myGemma' Diamond Weight PDF
  3. Use our Diamond Carat Calculator

Our diamond carat calculator is easy to use. It is a quick tool that requires you to input information on your diamond:

  • Shape
  • Length
  • Width
  • Height

In one press of a button, you will be given an immediate estimation of your diamond’s carat weight. However, if you are looking for definite measurements, a gemologist will need to use a diamond scale to weigh your stone. You will most likely need to remove your diamond from its setting to get the most accurate measurements. This process is best done by a trained gemologist to make sure that your diamond is being handled with proper care.


how to calculate diamond ct


4. How Does Carat Weight Affect A Diamond's Value?

As the weight of your diamond increases, so does its value. The reason being is because the rarer the diamond, the more it is worth. And larger diamonds are much rarer than smaller diamonds.

It is also important to note that there are significant price jumps between different diamond weights. For example, there is a big price jump between a 0.9ct and 1.0ct. Similarly, there is a significant price jump between a 1.9ct and 2.0ct.

But carat weight is not the only factor that affects a diamond’s value. The 4 C’s are widely regarded as the most important diamond characteristics when it comes to valuing a diamond. These are: carat weight, color grade, cut grade, and clarity grade.

5. When Do I Need To Use A Diamond Carat Calculator?

Should you be looking to sell your diamond, you will need to provide diamond buyers with the carat weight, clarity grade and color grade of your diamond to receive a price quote. Using myGemma’ Diamond Weight PDF or our Diamond Carat Calculator will help you obtain carat weight information from the comfort of your home.

As always however, a grading report from a reputable diamond-grading laboratory such as the Gemological Institute of America (GIA) will ensure a more accurate price range. The reason being is that laboratories provide highly accurate carat weights but also color grade, cut grade, and clarity grade.

6. Are Online Diamond Carat Calculators Accurate?

Online diamond carat calculators are tools that enable you to obtain a rough approximation for your carat weight. It is not recommended that you rely solely on this information. A diamond carat calculator does not cover all angles and facets of your diamond. A grading report by a reputable grading laboratory like the GIA however will give you the most accurate diamond gradings.

7. Can I Get A Price For My Diamond Based On Carat Weight Alone?

No. To receive a price quote for your diamond, you will need to provide:

  • The carat weight
  • The shape of your diamond (round, oval, pear etc.)
  • The color grade (grades range from D-Z)
  • The clarity grade (grades range from FL-I3)

If you are looking to sell your diamond and are missing information on your stone, simply call us to find out how best to obtain this information or to schedule an appointment with our gemologists.

If you have this information, simply fill out our online form. Our team of GIA-trained experts will then be in touch shortly with a free price valuation. With an A+ rating from the BBB and hundreds of online reviews from customers, you can rest assured that you are working with a world-class company that will take the safety and security of your diamond seriously. The entire process is free of charge and can take as little as 24 hours.