Diamond Carat Weight – The Fourth “C”

by J. Christopher Guritz

Not to Scale

Diamond Carat weight is very easy to understand when it comes to values and costs. The heavier the diamond is the more rare it is and therefore more costly – all other things being equal. The carat weight or size of the diamond is the “S” in the BPS  system.  There are a few things that I suggest – one being – buying your diamond loose. When you buy the diamond loose you can weigh it on a scale to confirm the diamond and its weight. This scale should be NTEP certified.


In certain states you will see seals where a scale has been tested for tolerance once a year. Like California’s  Type Evaluation Program and the Standard and Measures Seal.  46 States require legal for trade certifications.

This is a short podcast where I don’t go into all the stuff about how a diamonds weight is the easiest characteristics to measure, and where the term carat comes from. (Early traders used the carob seed to weigh their diamonds because they are incredibly consistent in weight.)

Or the fact that  the carat is a metric weight of 0.2grams or 1/142 of a standard ounce. (YAWN!)

I do talk about how a diamonds weight is divided into 100 points. So a half carat diamond reads 50 points and is written as .50ct, three quarters of a carats is 75 points and written .75ct etc. This way you’ll figure out if its ok to stay out of hot price ranges – or if it is important to buy an exact 1.00ct – because (all things being equal) you might be able to buy a .90 ct  and visually they are going to look similar as well as save some money too.

I stress the fact that you should buy your diamond loose. Buying loose allows you to get an exact carat weight for identification.  Only calculated guesses can be made once it is set. Buying loose also allows you to place the diamond in a performance device for viewing.

And last a diamonds carat weight has no influence on the other 3Cs.

My short notes.


Diamond Carat Weight – The Fourth “C”

The Foruth “C” Cut on the GIA

National Type Evaluation Program

Rates scales for tolerance in commercial weighing and measuring equipment
in the United States

  1. Why is Carat Weight Important
    1. Carat Weight and Rarity!
      1. How Weight Affects Cost
      2. What about shape & weight?
    2. Hot Ranges
      1. Increase
      2. Decrease
      3. The Feel Good
    3. How shape affects weight
      1. Performance
        1. Weight!


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