Inclusions & Blemishes

Diamond Blemishes: Extra Facet | Rare Carat

Diamond extra facet on a GIA Certificate

If you are not quite sure why you are reading a post about extra facets on a diamond, I advise you to take a little step back in the series (OK not a little, right back to the start), so you can get up to speed on what inclusions matter, where you might find them, and what they might mean for your potential ring. Click here for the introductory blog post on all things ‘inclusions’, and arm yourself with the basics.

Extra facets are pretty much what you’d expect, to be fair. Think of it this way; if ‘facets’ are those teeny tiny ‘faces’ or angles on a diamond, then extra facets are just additional facets/face/angles on top of the usual number needed for the stone to be characterized as a round/asscher/emerald/cushion cut etc., etc.

A round diamond against a gray background has a red circle and arrow pointing to an extra facet on the table

“Should an extra facet be a deal-breaker for me?” Well, although extra facets can occasionally mess with the symmetry of the diamond (but only minimally so), there is almost always a very clever reason for them to be there. Extra facets are a fantastic way to get rid of original unsightly blemishes, while making the stone even more sparkly! In fact, these facets are so chill, that they are not even considered when a diamond grader is determining the grade of a stone.

So instead of getting your pants in a twist if you see ‘extra facet’ on that diamond grading report, think of that clever diamond cutter who transformed that stone from ‘OK’ to ‘DAMN, YOU FINE!’

Extra Facet Diamond Blemishes FAQs

What exactly is an “extra facet” on a diamond?

An extra facet is simply an additional flat surface on the diamond—one that isn’t part of the standard facet pattern for its shape. The article explains that cutters sometimes add these extra facets intentionally to remove an unwanted blemish or inclusion or to improve yield from the rough stone.

Should I worry if a diamond’s certificate mentions “extra facet”?

Not always. In many cases, the article points out that extra facets are harmless and may even hide a blemish while improving the stone’s sparkle. The grading labs don’t usually penalize extra facets in clarity grading. However, if the extra facet is large, disrupts symmetry, or sits in a place that affects light performance, it’s worth a closer look.

How can an extra facet affect a diamond’s appearance or performance?

When done well, an extra facet can actually enhance brilliance by removing a flaw and creating more reflective surfaces. On the flip side, if it’s poorly positioned or disrupts the balance of the stone’s facet structure (for example, near the table or a girdle edge), it might affect how light travels through the diamond and slightly lower its visual performance.

What should I ask or look for when a diamond listing notes “extra facet”?

You’ll want to ask for detailed photos or videos of the diamond and check the grading report for any comments about symmetry or additional facet activity. Also, examine the light performance—does it still sparkle evenly? If you’re unsure, a specialist’s or gemologist’s input can help decide if the extra facet is benign or significant.

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Dr. Rian Mulcahy

Rian is officially a Diamond PhD - just ping us if you’d like to read her fascinating 200-page thesis, titled Facets of Value: An Investigation into the Formation of Worth in the Diamond Market. She has consulted various firms all along the pipeline, from the rough diamond market to the recycled diamond industry. She holds an MA in Globalisation and Development from University College Cork and a PhD in the Sociology of Diamond Valuation from the London School of Economics.