Understanding Diamond Cut: The 4Cs of Diamonds
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What is Diamond Cut

The cut of a diamond refers to how well the diamond’s facets interact with light, the proportions of the diamond, and the overall finish of the diamond.

It is not to be confused with the shape, (like emerald or round,) or facet arrangement, (like brilliant, or step cut), but is instead a reference to the craftsmanship of the diamond and how it factors into the diamond’s brilliance.


How Cut is Graded

AGS grades cut on a scale from 0 to 10, with 0 being “Ideal” and 10 being “Poor.” AGS has a proprietary numeric and verbal descriptors for cut. The numeric descriptors for the Diamond Cut Grade follow the American Gem Society's standards for how well a diamond is cut. The verbal descriptors are AGS Ideal, Excellent, Very Good, Good, Fair, and Poor.


What is an AGS Ideal Diamond?

AGS Ideal applies only to the finest cut diamonds and is recognized worldwide as the pinnacle of diamond cutting. Be careful if a jeweler tells you that a diamond is an Ideal. It’s not a real Ideal unless it is an AGS Ideal.


The Bottom Line

Keep in mind that a well-cut diamond will have more life and sparkle than one with a lesser cut quality. Not only will an AGS Ideal cut diamond have more sparkle, but it can even appear to have a better face-up color or clarity!

And, if you compare a well-cut small diamond side by side with a slightly larger diamond of lesser cut quality, the smaller diamond may look larger to the naked eye.

Overall, it’s important to have your diamonds graded by a credentialed expert or a reputable diamond grading laboratory such as American Gem Society Laboratories. You need a certified appraiser that truly understands the Ideal diamond cut.

Look for AGS jewelers to find reputable AGS member stores, and remember to ask for an American Gem Society Laboratory graded diamond.


Tips from AGS:

  • A well-cut diamond will have more life and sparkle than one of lesser quality.
  • If you compare a well-cut small diamond next to a slightly larger diamond of lesser cut quality, the small diamond may well look larger to the naked eye.

Mission Statement

The American Gem Society (AGS) is a nonprofit trade association of fine jewelry professionals dedicated to setting, maintaining and promoting the highest standards of ethical conduct and professional behavior through education, accreditation, recertification of its membership, gemological standards, and gemological research.

The Society is committed to providing educational products to inform and protect the consumer and to contributing to the betterment of the trade by creating industry standards to protect the jewelry-buying public and the fine jewelry industry as a whole.

AGS Laboratories, founded to support the AGS mission, is a nonprofit diamond grading laboratory with a mission of consumer protection. Adhering to the AGS Diamond Grading Standards, AGS Laboratories is dedicated to offering diamond grading reports that provide consistency and accuracy based on science.

American Gem Society