Two loose diamonds sitting on a table.

4 C's of Diamond Grading: Recipe for Rip-Off

The 4 C’s of Diamond Grading are important but do not tell the complete story. The 4 C’s are primarily used by retail sellers as a selling tool for customers.

Understanding much more is essential to make an informed buying decision. If you do not know the game’s rules, it’s nearly impossible to win, otherwise you rely on luck.

The 4 C’s are important, but offer limited intel. Without insider information, they can be seen as a rip-off.

Our 8 Insider Tips:

1. Lighting

Be aware of your surroundings! Jewelry stores spend thousands of dollars on lighting. They want their products to look as impressive as possible.

But it’s not real! The best way to view a diamond is under natural light, hop outside, or by a window. If this is not possible, try shielding the light with your hand to get a better sense of the color and sparkle.

2. Depth % and Table %

Every diamond shape has different %'s to get maximum light flow, thus, maximum sparkle.

There have been countless times when someone walks into a social setting, and their diamond lights up the room, sitting beside someone with a diamond twice the size. The person with the bigger lifeless stone will cover theirs up and start making excuses; it needs to be cleaned, reset, etc.

Sparkle says more than size. The more sparkle a diamond has, the more prominent it appears. If you care about sparkle, KNOW YOUR MATH!

3. Understand Girdle Thickness

The girdle is often used to manipulate the weight of a diamond. We recommend thin, medium or slightly thick. Too thin and the diamond is prone to chipping and too thick adds additional weight and $$$

Girdle thickness chart showing examples of the different degrees of diamond thickness.



To illustrate further, let’s pretend that two stones have a diameter of 6.2mm, so they look the same from the top view or when set.

But the one on the left weighs 0.95 carat and the one on the right weighs 1.01 carat.

That extra weight is a quick profit for the seller of an uninformed customer. Depending on the grade, it could increase profits up to $2K.

4. Fluorescence

There are a lot of different opinions on this characteristic; we can tell you that the wholesale price drops significantly depending on the fluorescence of the diamond.

In some cases, it will cause the diamond to look hazy or foggy. We highly encourage you to accept the grade of None or Faint.

5. Clarity Characteristics

NO Diamond dealer will buy a diamond without magnifying the diamond.
Be careful with microscopes. Most have a lot of controls. Sellers can make a great diamond look bad, and can do the reverse to make a low-grade diamond look great.

If you can get comfortable with a 10x loupe, there are no controls to manipulate. But, we recommend to always look under a microscope as well. Just be aware that if you need to familiarize yourself with the device, that too can be used as a selling tool.

6. Loose Diamonds

Most diamond dealers will only purchase a diamond if it is loose (unset).

It’s amazing what you can hide under a prong! There are many types of inclusions/flaws; please keep in mind, the location of flaws matter too.

Examples of diamond flaws to understand with the 4 C's insider tips.



We highly recommend staying away from Cavity, Chip, Indented Natural, Laser drilling, and Twinning wisp flaws.

7. Laser Inscriptions

Becoming more and more common in the marketplace. It is a unique number & logo lasered into the girdle of the diamond. Think of it as a VIN number for your diamond.

Make sure the number matches your paperwork.

When the time comes when you need your piece serviced, i.e. ring sizing, I would suggest looking at your number with your jeweler/goldsmith before and after the work is complete

Just a quick check to ensure no mistakes or improprieties occurred.

8. Polish & Symmetry

These both influence the optical appearance of your diamond, both reflection & scintillation. We recommend looking for a grade of Excellent or Very Good.

Choose Carbon Diamonds

Now that you know how much goes into selling and buying a diamond, you can understand why the 4C’s do not provide all of the information necessary to make a truly informed decision.

This is the kind of education Carbon Diamonds prides itself on offering before ever selling to a customer.

Make an informed choice, contact us today for an exclusive private appointment at our showroom or schedule a virtual meeting.