How Diamonds Are Graded - And Why You Should Care

How Diamonds Are Graded - And Why You Should Care

 So, you’re ready to buy a diamond but don’t know how to tell a shiny rock from a priceless gem. Well, you’re in luck, friend. 

While all polished diamonds are worth something, not all of them are worth your time or your hard-earned money. Diamond grading provides a guide that anyone, from diamond dealer to  blushing bride, can use to determine the value of an individual diamond. 

But how important is it to grab a graded diamond, and how do you read a certification anyway? Let’s get into it. 

A, B, C, Diamond 

What exactly is diamond grading anyway? Simply put, it’s an industry-wide standardized process of determining a diamond's quality. 

Labs like GIA, IGI, and AGS (just to name a few) run tests on each individual diamond. The quality of each stone is broken down into several categories. These categories can each be seen on the diamond report. 

The overall scores of each category (things like clarity, color, and more) combine to tell us how valuable each stone is. 

Radiant Cut Diamond image

Radiant Cut Diamond

Grade Guardians 

So, who’s actually doing all this diamond grading? While technology is beneficial and used throughout the process, the actual grading is done by people. 

These highly trained diamond graders study each stone for color, clarity, and cut. Not to mention all of the tiny details in between. This is an incredibly detail-oriented process. At least two diamond graders check each stone to ensure an accurate and impartial grade. 

An unbiased opinion is crucial, so each stone is also given a number as it comes into the lab. Graders never know where the stones came from. This anonymity provides another level of assurance of the equality of each diamond and its grading process.

Emerald, Cushion, Oval, Pear, and Radiant Diamonds  image

Emerald, Cushion, Oval, Pear, and Radiant Diamonds

Study Sesh

Just how does that meticulous grading get done? Each stone is carefully studied by experts, one gem at a time. 

For color, each stone is compared to a set of actual round brilliant diamonds that have been set up as a color scale. These are called masterstones. 

Diamond Color Grades</b><b> image

Diamond Color Grades

Clarity is also measured by expert graders, this time by close and detailed observation. This is done using a 10x magnification loupe and a microscope. Inclusions and blemishes are mapped on a diamond chart. This shows the type of inclusion and its precise location. 

During this step, graders also look for treatments that may have been done to improve the diamond artificially. This will also be noted in the report.

Here are a few inclusions they are looking for.

• Pinpoint inclusions or tiny black spots. 

• Diamond cavities, which are small holes within the diamond

• Feather inclusions are tiny cracks inside or on the surface of the diamond.

The combination of location, size, and the number of inclusions, as well as whether or not they can be seen with the naked eye, all affect the diamond's clarity grade. 

Example of a GIA Clarity Chart Showing Inclusions for a VS2 Round Diamond image

Example of a GIA Clarity Chart Showing Inclusions for a VS2 Round Diamond

Check your work

Gemologists always check their work. A diamond is graded for color and clarity by one gemologist, then passed to another for a second opinion. This second grader forms their opinions entirely independently from the first. 

These reports are compared and finalized when a consensus is reached on the diamond's quality. If things don’t quite add up, a third opinion may be called in from a senior gemologist. This ensures the most accurate grade possible for each diamond. 

The Bottom one is a 3 carat G SI1 Cushion cut Lab diamond, the Middle one is a 2.66 carat H VS2 Radiant cut Diamond, the top one is 1.15 carat F VSI Round Brilliant cut Diamond  image

The Bottom one is a 3 carat G SI1 Cushion cut Lab diamond, the Middle one is a 2.66 carat H VS2 Radiant cut Diamond, the top one is 1.15 carat F VSI Round Brilliant cut Diamond

Does it Pass the Test?

Do you need to buy a certified diamond? Well, it’s certainly recommended. 

Diamond certification ensures the buyer and seller both know the fair value of the stone. An uncertified diamond might look great, but you have no way of knowing the actual value. This could lead to you overpaying or going home with a lousy diamond. 

Certification means you know exactly what you are getting, and diamond dealers know exactly what they’re selling. So it’s definitely to the benefit of both parties to snag that certification. 

Pear Cut Diamond image

Pear Cut Diamond

POP Quiz

What are diamonds graded for, and how do you know which diamond is the best?

Choosing a diamond can be overwhelming. Starting with a budget and having a style in mind are great jumping-off points. But grading is where you can really narrow down what it is you want in a stone. 

The most common things to look for, and easiest to understand, are called the 4C’s.

C’s Across the Board

Cut is one of the most important factors when buying a diamond 

• A well-cut diamond will be sparkly and bright

• A poorly cut stone will be dark and dull

• Only round brilliant stones are graded for cut

• This grade is based on symmetry, facet position, polish, shine, and culet size.

3.01 carat G-SI1 Cushion Cut Diamond image

3.01 carat G-SI1 Cushion Cut Diamond


Diamond color is graded on a scale. 

• D represents colorless, Z light color

• It is not essential to buy a completely colorless stone

• A G-H color stone will be less expensive and still appear colorless

• A diamond's fluorescence can also affect the color. Blue fluorescence can make a yellow stone appear more colorless 

The top one is a 1 carat Oval F VS1 Natural Diamond and the bottom one is a 3.17 carat Oval D VVS1 Diamond image

The top one is a 1 carat Oval F VS1 Natural Diamond and the bottom one is a 3.17 carat Oval D VVS1 Diamond

Diamond color is graded on a scale

• The fewer inclusions, the more valuable

• But it is not necessary to buy a completely flawless stone, only an eye-clean one.

• The location of these inclusions is also a key factor in visibility

• Inclusions near the table will be easily visible

• Inclusions near the edge can be a structural concern

• A certification will mark the location and type of inclusions 

Carat Weight is the specific unit of measure 

• Carat weight was developed for gemstones and diamonds

• Very precise measurement

• One carat is 0.2 grams or 0.007 ounces

• The slightest variation can mean hundreds of dollars depending on the quality

• A diamond's weight does not necessarily tell you its size as this can vary slightly due to other factors.

The combination of all of these factors shows us the diamond’s quality. Understanding the quality (and which areas are most important for your needs) can help you go home with a better diamond for your budget. 

</b><b><span>Different Carats of Oval Diamonds On Hand</span> image

Different Carats of Oval Diamonds On Hand

The Final Presentation 

Diamond certification levels the playing field. It ensures that buyers and sellers alike know the quality and fair value of all those tiny shinies. 

The grading process can seem complicated. But when you know what to look for, a good cut, an eye-clean stone, and a colorless appearance, finding the right rock can be as easy as ABC. Or VVS in this case. 


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