Complete Guide to the Diamond Girdle

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?

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. There are three types of diamond girdles: the standard polished girdle, the faceted polished girdle, and the frosted girdle. Additionally, the diamond girdle comes in many different thicknesses and styles with many gradings, all of which should appear on your diamond certification report.

Almost every diamond cut has a girdle, although it will vary dramatically in style and size depending on the cut and age of the diamond.

If the diamond is certified, the certification company may also place a unique laser inscription onto the girdle. This inscription helps identify the diamond and link it to its grading report.

Diamond Girdle Terminology

Four important factors are needed to understand the diamond girdle. Each factor is important to consider when analyzing your diamond.

1. Girdle Width

The width of the girdle 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.

Skip to the section about girdle thickness.

2. Girdle Facets

As we will discuss below, there are two types of girdle faceting: the single-facet girdle and the faceted girdle. The faceting style can enhance a diamond’s light performance and brilliance. It is also a big artistic choice.

3. Girdle Transparency and Finish

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.

This enters into the big debates between those who favor the frosted or faceted diamond girdle.

4. Girdle Alignment

The alignment of the girdle contributes to a diamond’s overall beauty and symmetry. Proper alignment makes the facets proportioned and positioned correctly, which adds to harmony and aesthetic appeal.

Poor alignment should be easy to spot with an x10-powered loupe.

What Is a Frosted Diamond Girdle?

A frosted girdle (or bruted 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 to find a choice that meets your needs.

Important Note: Although not correct terminology, the frosted girdle is also known as the “bruted girdle.” In modern lingo, they are the same thing.

Pros of a Frosted Girdle

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

Cons of a Frosted Girdle

• This texture is less common than its polished counterpart, making it harder to find.
• The original elements of the diamond are changed because frosting involves etching or treating the surface.
• It’s not an excellent choice for individuals who prefer a sleek and modern look.

What Is a Polished Diamond Girdle?

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 smooth when you slide your finger across it, 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 and 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.

Pros of a Polished Diamond Girdle

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

Cons of a Polished Diamond Girdle

• Fully polished girdles can contribute to the diamond’s overall weight, possibly increasing costs.
• Since it’s widely available and standard, many will likely have the same girdle type.

Understanding the Thickness of the Diamond Girdle

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.

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 understand them better.

A. Extremely Thin

In this case, the girdle is almost invisible because of the thin outline. In some cases, it’s prone to breaking or chipping. 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

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

You can 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

This is an almost perfect grade with a higher-than-medium girdle thickness. The diamond depth isn’t affected, and 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

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 desirable for that ideal diamond cut.

F. Very Thick

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

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.

Final Notes on 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 remember.

1. Girdle consistency shouldn’t be too thick as it results in dead weight, which makes the diamond look smaller.
2. 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.
3. 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.
4. 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

Do you have any questions about diamonds? Or are you ready to buy a diamond?

Reach out to us, and we will respond within one business hour.