What is a Diamond Girdle?

Feb 17th 2022

What is a Diamond Girdle?

You’re preparing to pop the question and scouting around for a fancy engagement ring to make sure that she’ll say “yes.” While ring design is important, you’ll also want to pay attention to diamond qualities, like the girdle. Not sure what a diamond girdle is? We’re here to help, so you can choose a sparkler that will light up her hand and heart!

What is a Diamond Girdle?

To get you started, the girdle is a thin border around the widest part of a diamond. Think of it as the circumference when you’re viewing the stone from above. If you’re looking at the side of a diamond, the girdle also divides the top part of the stone (aka crown) from the V-shaped, bottom portion of the diamond (aka pavilion).

With the naked eye, the girdle just looks like a thin line. But girdles can actually have various thicknesses, which are measured under a microscope at 10x magnification. You might see girdle specifications listed as a percentage of the diamond’s diameter, or you might come across written descriptions. Since thickness tends to fluctuate throughout a diamond, girdles are usually measured at their thinnest and thickest points. Therefore, they’re often rated in a range (ex. thin-medium). You’ll typically see the following categories.

  • Extremely Thin
  • Very Thin
  • Medium
  • Slightly Thick
  • Thick
  • Very Thick
  • Extremely Thick

So, why is all of this important? You may have already guessed that the girdle is used to determine overall diamond measurements. But it also affects a diamond’s sparkle and durability. For example, jewelry experts advise against choosing a stone with an extremely thin girdle, as it’s more likely to chip and break. Since diamonds are often secured near the girdle, this feature needs to be durable. On the other hand, light reflects differently in certain diamonds with extremely thick girdles, resulting in less brilliance and a duller appearance.

Jewelry experts agree that a medium girdle is the best choice, as it reflects light well and is unlikely to chip. However, thin and slightly thick girdles also work well for round cut diamonds. If you’re eyeing fancy cuts, like marquise or heart-shaped diamonds, you’d be safe with girdles ranging from thin to thick.

It’s also worth noting that girdles come in a few different styles: unpolished/bruted, polished and faceted. Unpolished/bruted girdles are no longer considered fashionable in engagement rings, as they feature a rough surface and limit a stone’s sparkle. You can find polished girdles on round and princess cut diamonds as well as diamonds with step cuts (aka rectangular or square facets that are arranged as a set of steps). But faceted girdles are most popular. They include multiple flat, polished surfaces along the edge of the diamond, creating maximum sparkle.

*Pro Tip: When shopping, keep in mind that colored diamonds usually have thicker girdles. Yellow diamonds, in particular, are known to have extremely thick girdles.

Is There a Crack in My Diamond?

At times, you might notice a line running through the bottom half of your diamond. You might wonder, “Is there a crack in my stone?” If you have been careful with your ring, don’t worry just yet. It could be a girdle reflection instead.

What’s a girdle reflection? Well, it’s simply a reflection of the girdle, not an imperfection in the diamond’s clarity. When light enters a diamond, it sometimes hits the girdle and exits through the pavilion/bottom portion. Reflections are more pronounced in stones with unpolished/bruted and thicker girdles.

But if you’re still feeling uneasy, you can always check with a jeweler!

Have a question? We can help!

Gage Diamonds is Chicago's premier jewelry showroom and online retailer of engagement rings, wedding bands, and fine jewelry. We offer a selection of dazzling handpicked diamonds, including certified natural diamonds.

We’re committed to helping you find the ring of your dreams. For inspiration, browse our website or set up an appointment with a member of our trusted staff at our in-person showroom.

We offer no-credit-needed financing – feel free to apply and get your approval within 24 hours!

Pay over time, because love shouldn’t wait.