Everything You Need to Know About Diamond Symmetry

Pear and Radiant cut Diamonds

A diamond’s symmetry contributes to its sparkle, its cut grade, and its overall appeal. But what makes a diamond symmetrical, and how can you tell? Read on to find out!

What is diamond symmetry?

“Symmetry” doesn’t mean that a diamond’s two halves are mirror images of one another. Instead, “symmetry” describes the degree to which a stone’s facets are properly aligned with each other. In this sense, a “symmetrical” diamond is more well-proportioned than strictly symmetrical. The alignment of the facets, crown height, and crown angles can all affect the symmetry of a diamond.

Why is diamond symmetry important?

A diamond that has good symmetry reflects and refracts light well, generating maximum brilliance and fire. A diamond with poor symmetry either absorbs light or reflects too much of it. This makes for a dull diamond - and also accentuates any flaws and coloration in the stone.

While symmetry isn't one of the 4 C’s, it’s directly related to cut quality. An “excellent” or “very good” cut grade means a diamond has outstanding symmetry. A “poor” grade - less so.

What causes poor symmetry?

Flawed facets, an off-center table, or a misplaced culet can all lead to poor symmetry. Facets that are not pointed properly, a table that is not parallel to the girdle, and the crown and pavilion being out of alignment can also contribute to poor symmetry.

Does my center stone have good symmetry?

The best way to know is to look at a diamond’s cut grade, which is measured on a scale from “excellent” to “poor”. Diamonds graded as “excellent” have excellent symmetry. Centered tables, no missing or extra facets, etc. A “very good” cut grade could point to some small deviations, e.g. a few imperfectly pointed facets.

The blue arrows represent light reflection off of the diamond. Excellent-cut diamond reflect light best, as no light escapes through the bottom of the stone. Diamonds graded as “fair” might have multiple deviations from standard anatomy and misshaped facets, etc.

Diamonds with a “poor” cut grade will have unmistakably poor symmetry. Their facets will look oddly shaped and misaligned. The table and culet will be visibly off-center. The diamond will have diminished sparkle as a result of its poor symmetry.

How does symmetry affect a diamond’s price?

Symmetry is assessed under 10x magnification. Diamonds with excellent symmetry tend to be more expensive than any other kind… But sometimes, a “very good” cut grade is visually identical to an “excellent” one. This is often the case with fancy shapes, but very rare for round brilliant stones.

Conclusion

While symmetry is not the only factor to consider when choosing a diamond, it’s an important aspect. Symmetry affects how brilliant and sparkly your diamond will be. Since you’ll be wearing your diamond for years to come, choosing a diamond with a high symmetry grade will ensure you love the way it looks for decades.

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