How To Grade Diamonds

Want to know how to grade diamonds before buying THE ring for that special someone?  You may not have all the skills and equipment required to accurately grade diamonds yourself, but there are some basic pieces of information to arm yourself with, to make sure you aren't taken in by a less than scrupulous salesperson. There are four basic criteria that are used to determine a diamond's value. These are carat weight, clarity, color, and cut. You will also want to consider the diamond grader, the shape of the diamond, and the way the diamond was mined. (These are in the "beyond the grade", section.)

  1. Carat weight. Of the four Cs used to grade diamonds is carat weight. Carat weight is the easiest  to determine, as a carat is universally equivalent to .2 grams. You may also hear a diamond’s weight referred to in “points”. When measuring in points, you need to remember that 100 points is equal to 1 carat. So a 75 point diamond is ¾ carats.(It’s interesting to note that, until this century, diamonds were measured by finding their weight in carob tree seeds. This is where the word “carat” comes from.)
  2. Clarity. This element is a little trickier to determine. Every natural diamond has tiny deformities which occurred in the magma from which diamonds form. Irregularities within the diamond are called “inclusions". Diamonds range from the nearly impossible “flawless” to “heavily included”. Clarity can only be determined by an experienced grader under magnification.
  3. Color. Diamond color ranges from colorless on one end of the spectrum to yellow and “fancy color” diamonds on the other. For the purpose of grading diamonds, it’s the clearer the better. Color is sometimes determined by machine, but the best grading is done by a pro who compares the diamond to a “master stone” under specific lighting conditions.
  4. Cut.   A high grade cut is the one factor that is created rather than born. While diamond graders look at cut in terms of angles and percentages, a quality cut is also fairly apparent to the consumer. The best cut has the most sparkle. So if it doesn’t flash, it’s not worth the cash.

 Beyond the Grade

  1. Graders. As most of the four Cs used for grading diamonds depend on the fallible human eye, a single stone may receive a different grade depending on he grader. So unless you are an expert yourself, you will need to know a bit about graders. The most reputable diamond  graders are  AGS  (American Gemological Society) and GIA (Gemological Institute of America). Though there are other reputable graders, these two tend to be tougher in their grading. So if they say it’s a good stone, it is.
  2. Shape.  Shape is not considered in a diamond's grade, but might help determine what a diamond is worth to you. The first of these is shape. Shape is often confused with cut. But while cut determines the way light plays off the stone, shape is about presentation. Round is classic, but there are quite a few other options, from the rather solid rectangle of the “emerald” cut, to the romantic “heart” cut. This is where the personality of the wearer should be considered most.
  3. Conscience. The final factor is considered by many to be the  fifth “C”: conscience. Many diamonds are obtained by means which violate human rights and fund civil war efforts. Now consumers can purchase diamonds which are certified as “conflict-free”. These diamonds are mined in ways which, according to the U.N., are free of violence and human rights abuses. In addition, their mining is less destructive to the environment. This final factor may or may not change the price of the stone, but could add great value to the purchaser and the receiver.

 Now that you’re armed with information, go out there and pick that perfect diamond. Hopefully their “I will” makes all the careful planning worthwhile. Good luck!



Diamond 4 C's


Diamond Shape

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