Jewelry Blog

Complete Guide to the Diamond Girdle

What is a diamond's girdle infographic with images

In this article, diamond expert Afshin Shaddiae explains everything you need to know about the diamond girdle. He also explains the difference between a frosted and polished diamond girdle.

Learn why these details matter for the quality and look of a diamond, especially in antique diamonds.

What Is a Diamond Girdle?

Diagram of brilliant cut diamond's girdle

The girdle (a.k.a. the diamond’s “belt”) is the thin rim that joins the crown and the pavilion and extends around the entire circumference of any diamond. Since a diamond’s largest diameter will be at the girdle, that’s usually where the stone is held in place on its setting.

Every diamond, regardless of cut, has a girdle that varies in style and size. This part is normally graded, and such information appears on the certification report.

If the girdle is certified, it can also have a unique laser inscription. This inscription aids in identifying and linking it to the grading report mentioned above. In most cases, the size around the diamond is not uniform. As such, it is normal to get two girdle gradings in one report.

Five different factors set girdles apart, including:

1. Girdle Width

diagram of diamond girdle width

Normally, the width varies from thick to thin. Thick girdles add visual weight and may be a good choice in some designs and shapes. However, an extremely thick girdle can affect the cut grade of the stone and light performance.

In contrast, thin girdles result in smaller-looking stones. A girdle within the thin to slightly thick range is a good choice for light return and durability. However, it shouldn’t be too thin because it would be more likely to chip.

2. Girdle Facets

diagram of diamond girdle with facets

There are some cuts like a princess and round brilliant where additional facets may be present on the girdle. These are referred to as girdle breaks or girdle facets. The facets can enhance the light performance and brilliance of a diamond.

3. Girdle Transparency

diamond girdle diagram showing transparency

In most cases, girdles are transparent. However, there are opaque and semi-translucent options as well. The transparency of a girdle, or lack of it, creates some unique visual effects, especially related to how light interacts with it. A choice can be made based on this individualistic and distinct appearance.

4. Girdle Alignment

diagram of faceted diamond girdle

Alignment, combined with other diamond features, contributes to the overall beauty and symmetry of a diamond. With proper alignment, the facets are proportioned and positioned correctly, which adds to harmony and aesthetic appeal.

5. Girdle Finish

diagram of diamond with rough finished girdle

This mainly affects the overall girdle aesthetics. The most common option here is a polished finish, but bruted and frosted finishes are available as well. The option you choose depends on the appearance you want.

What Is a Frosted Diamond Girdle?

diagram of frosted diamond girdle

A frosted girdle refers to a matte or textured finish generally applied to the diamond girdle, resulting in a frosted appearance – hence the name. This finish may add a visual element to the stone. It can be picked to enhance the overall design.

With a frosted girdle, there is a subtle contrast against reflective surfaces in the other diamond facets, making it stand out in uniqueness and beauty.

It also makes some room for personalization, allowing individuals to enhance the character and design of the diamond.

Please note that if you are considering this option, it is not as common as other options. Therefore, it is wise to consult a diamond expert for assistance and guidance in finding a choice that meets your requirements.


  • Unique aesthetic: This finish adds a distinct touch to the appearance, making it a good choice for non-conformist enthusiasts.
  • Vintage charm: It’s a desirable option for those desiring a classic jewelry look.
  • Softened brilliance: The texture diffuses and scatters light differently, creating a softening effect on light reflections.


  • Limited availability: This texture is not as common as its polished counterpart, which makes it harder to find.
  • Permanent alterations: The original elements of the diamond are changed because frosting involves etching or treating the surface.
  • Not versatile: It’s not a great choice for individuals who prefer a sleek look.

What Is a Polished Diamond Girdle?

gemstone with polished girdle diagram side view

A polished girdle means a diamond’s outer edge is refined to have a smooth, shiny finish. This finish allows you to see through the stone. The whole girdle area is clean and smooth all around, with no signs of roughness. A polished girdle can be a single smooth facet or multi-faceted.

This is a standard finishing, especially in modern diamonds. Polishing the girdle serves various purposes, the most notable being enhancing aesthetics, making the precious stone more appealing. The surface reflects light, further enhancing the diamond’s sparkle and brilliance.

Polished girdles have practical benefits because handling this type of diamond in the setting process is much easier. There are fewer chances of damage or snagging. It is quite unlikely that a polished diamond can chip on the edges, which gives it superior structural integrity.


  • Enhanced brilliance: Since the option allows light through, sparkle and brilliance are maximized. The surface refracts and reflects light better, enhancing its beauty.
  • Versatility: The choice compliments different diamond designs and shapes, integrating seamlessly with various settings.
  • Symmetry and consistency: It’s easier to match with jewelry sets. The uniformity contributes to the visual appeal and harmony of the overall look.


  • Added weight: Fully polished girdles can contribute to the diamond’s overall weight, which may increase the cost.
  • Lacks uniqueness: Since it’s widely available and common, many will likely have the same girdle type.

What Is a Bruted Diamond Girdle?

diagram of bruted girdle

A bruted girdle refers to a finish where the girdle is left in a natural state without additional faceting or polishing. This leaves it with a slightly irregular, unpolished, and rough texture, giving it a grainy look. Bruted girdles are also called natural or raw girdles.

The creation process involves rotating and grinding the diamonds against one another to create the desired proportions and shapes.

Usually, irregular striations or facets are present due to the bruting process.

Why Leave It Bruted?

vintage diamond with bruted girdle on tweezers

A diamond may be bruted for several reasons, including:

  • Cutter preference
  • Desired aesthetic
  • Preferred shape
  • Preservation of carat

Although the bruted girdle is less refined than the polished option, its roughness contributes to its uniqueness and beauty. It is especially a good option for those who want a natural and organic aesthetic. The feature also gives the diamond more character.


  • Distinctive appearance: The raw and unpolished texture gives the diamond a more natural and organic aesthetic.
  • Vintage charm: Bruted girdles are reminiscent of older techniques, which gives them a vintage charm.
  • Potential savings: They don’t have a high demand like the polished options, which makes them a bit more affordable.


  • Lower brilliance: Without polishing, light reflection is not as efficient. This reduces the sparkle and brilliance of the diamond.
  • High chances of chipping: Rougher texture equals higher damage and chipping vulnerability because of the exposed edges.
  • Limited availability: This option is less common, making it hard to find specific quality grades, sizes, and shapes.

Which Girdle Is the Best?

round brilliant cut diamond graphic side view

Choosing a girdle is a matter of preference, which makes the best option quite subjective. Each girdle has specific characteristics, which should ease decision-making.

Bruted Girdle

The bruted girdle should suffice for those who prefer a natural, organic, and distinctive appearance. This type of diamond is individualistic and has a raw look. It is also an ideal option for those who prefer the preservation of the carat weight. The polishing phase typically removes thin material layers, which influences the weight.

Polished Girdle

Those who prefer enhanced elegance and beauty should select the polished girdle. Polishing removes the irregularities and roughness for a smoother, resistant surface that is less likely to chip or damage. This makes the option a durable one. Its appearance is consistent, and the most preferred diamond in the market.

Frosted Girdle

Anyone who loves an unchanged and genuine vintage can’t go wrong with a frosted girdle. It has understated and subtle beauty compared to the other options. The visual effect is unique since light is scattered and diffused differently than in other finishes. It offers a personal textured style that conceals minor imperfections on the diamond’s surface.

Understanding the Thickness Amounts of the Girdle

graph of diamond girdle thickness

Like any other diamond attribute, the girdle has a grading scale. This scale can be based on width, thickness, and overall appearance. Girdle thickness doesn’t have a standardized grading scale. However, the industry uses descriptive terms to communicate and assess the characteristics.

Jewelers use girdle grading to identify the largest and smallest sizes using optical measuring devices meant for gemstones.

Measuring thickness involves:

  • Preparation: Involves securing the diamond on a clamp or holder for stability and safety.
  • Picking measuring points: Specific girdle points are picked based on the shape. Normally, these points are evenly distributed on the circumference.
  • Measurement: The measuring tool’s (usually a micrometer) jaws are positioned on either side of the gem at the measurement points picked. The micrometer is then closed gently, coming into contact with the girdle. Measurements are read from the tool indicating thickness in fractions of a millimeter or millimeters. To guarantee accuracy, multiple measurements are taken to account for variations.
  • Averaging measurements: Averaging helps determine overall thickness. It’s a representative value of the girdle’s average thickness.

Different thickness amounts affect a diamond’s durability and appearance. Thickness is not always uniform, even on a single gem, ranging from extremely thin to extremely thick. Let’s look at the girdle thickness amounts to better understand them.

A. Extremely Thin

Extremely thin diamond girdle diagram

In this case, the girdle is almost invisible because of the thin outline. In some cases, it’s prone to breaking or chipping. As such, it must be handled carefully when cutting and setting the stone. This thickness can significantly affect the diamond cut grade, with a diamond depth appearing relatively shallow.

B. Very Thin

diamond with very thin girdle

A very thin girdle needs extra care when the diamond is set because of a chipping risk. The grade has small outlines, with risks of damage or chipping, though not as high as the extremely thin option. It is a good girdle size for diamond cuts, but it’s not the best.

C. Medium

medium girdle diamond diagram

You can clearly see a perfect girdle with this thickness. The chipping and breaking risk is much lower, while the cut grade isn’t significantly affected. This is an ideal proportion for most diamonds and settings. The thickness is sufficient to handle pressure without being too thick to have an adverse effect on the depth of the diamond.

At times, you can get a thin-medium combination through some modifications.

D. Slightly Thick

diamond with slightly thick girdle

This is an almost perfect grade with a higher-than-medium girdle thickness. The diamond depth isn’t affected. The girdle doesn’t make it too deep, either. The risks of chipping and breaking are pretty low with this thickness, making it a good option.

E. Thick

thick girdle on a diamond

The girdle is quite thick, and the depth is slightly increased, affecting the diamond’s appearance. This girdle size often results in a Very Good cut grade. The thickness is higher than what is considered desirable for that ideal diamond cut.

F. Very Thick

diamond with very thick girdle

The girdle is much thicker than previous options and often yields high depth. The cut grade is Very Good or Good. The girdle reflection may be seen in a diamond of this size.

G. Extremely Thick

diagram of extremely thick girdle

Here, the girdle happens to be so much thicker than customarily recommended and is usually considered undesirable. The diamond’s symmetry is often affected, and the cut grade is reduced to Good or Fair. There is a high chance of a fisheye effect where the girdle reflection is visible within the diamond. This affects the diamond’s sparkle.

Things to Note About Diamond Girdle Thickness

A diamond’s girdle thickness is important when buying diamond pieces. Before you make a buying decision, there are several things to keep in mind.

  • Girdle consistency shouldn’t be too thick as it results in dead weight, which makes the diamond look smaller.
  • Extreme girdle variations aren’t the best because they can result in symmetry issues or poor cuts. In most cases, the diamond’s optical performance is lowered. The extreme variations lead to problems during the stone setting process.
  • Ratings are done relative to the stone size or the diameter. This means that a 0.31-millimeter thickness can result in a “Very Thick” rating for a half-carat diamond. However, the exact measurement in a 5-carat diamond may result in a “Thin-Medium” rating.
  • Extremely thin girdles result in knife-like edges where the crown and pavilion meet. Mechanically, the diamond’s crystalline structure is weakest at such edges, making it susceptible to damage.

Talk to a Diamond Expert

jewelry expert Afshin in jewelry showroom

When it comes to the choice between frosted, polished, and bruted girdles, it’s a matter of personal preference. Consult with a diamond expert to help determine which finish is best for your choices.

To help you decide, talk to our Estate Diamond Jewelry Experts. With years of experience, we can offer profound insights and ensure you pick the perfect option.


About Afshin Shaddaie

Afshin moved to New York City in the 1980s, and a few years later, he began his career in the fine and rare jewelry scene. He teamed up with Michael Khordipour, and they've been curating vintage jewelry ever since. He also regularly contributes to Forbes, Rapaport, CNBC, The Knot, and Insider. Afshin constantly travels to international shows and private viewing events in the hope of finding rare vintage rings that will be important enough to make an impression. He is available for appointments at our New York showroom when he's not traveling. In 2019, Afshin authored his book called The Engagement Ring Guide for Men. He is considered one of the world's foremost authorities on vintage jewelry and antique diamonds. His favorite jewelry era is Art Nouveau, and he loves rare Italian jewelry from the 1950s - 1970s. The Natural Saltwater Pearl is his favorite precious jewel.