Judging Diamond Quality

What to Look For

If you want to begin judging diamond quality, you must first learn and understand the 4 C’s, which are four characteristics of diamonds that give the gem stone it’s overall value. The 4 C’s for judging diamond quality include the diamonds color, clarity, carats and cut.

Judging Color

Most diamonds are considered to be ideal if they are transparent, or colorless. Diamonds that are rated as colorless are the most expensive of diamonds. The colors of diamonds are rated with an alphabet grading system that starts with “D” and ends with “Z”. Completely colorless diamonds fall in the “D” and “E” grade, while colored, fancy diamonds are at the other end of the alphabet, at “Y” and “Z”.

There are two main ways that jewelers’ use when judging diamond quality based on color. They may pull out a set of reference stones, and find the closest match between the diamond and the reference stone to determine its letter grade. Alternatively, the jeweler may use a colorimeter, which can electronically measure the color of the stone and determine its grade within 1/3 of a grade.

Judging Clarity

The clarity of a diamond refers to whether or not the diamond is clear all the way through, or whether it has tiny flaws and cloudy areas within the gemstone. It’s actually very rare to have a diamond with absolute perfect clarity and no flaws, but most diamond flaws are not visible to the naked eye and can only be seen with a magnifying device.

The Gemological Institute of America (GIA) uses a magnification of about 10x when judging diamond quality based on the clarity. There are treatments available to make a diamond appear nicer than it actually is, and the treatments should lower the overall price of the diamond so it is important to do your research before purchasing a diamond to be sure you are not spending more money than you should.

Judging Carat Weight

Carat is the term we used to describe the weight of a diamond gemstone. One carat is equivalent to 200 milligrams of weight. A single diamond with a high amount of carat weight is more expensive than the equivalent amount of carats in multiple stones. This is because finding the larger diamonds is much more rare of an occurrence. So if you want a 2-carat diamond ring, for example, you may decide to go with a half-carat diamond surrounded by smaller diamonds that add up to one and a half carats to give you the total of 2 carats! Judging diamond quality by the amount of carats is difficult, since different shaped gemstones, and stones with different levels of clarity will be priced differently even if they have the same amount of carats.

Judging Cut

One of the most important factors in judging diamond quality is judging the cut of a diamond. It’s important because a quality cut diamond will be more brilliant and reflects light more beautifully, and yet the cut of a diamond has the least impact on the overall price of the diamond.

When judging diamond quality on the cut of a diamond, look at the stone in a well lit area. If the light seems to go into the stone and bounce back, showing a sparkling reflective surface, the diamond has a good cut. The angles and shapes of a diamond are important to judging diamond quality and the overall appearance of your diamond.