Before we can talk about the issue of symmetry and girdle thickness, we first have to understand what makes up a diamond’s anatomy. The various parts of a diamond can be broken down into three main portions: 

  • the crown is the top part of the diamond. It consists of bezel facets, upper girdle facets and a large horizontal facet at the diamond’s center called the table.
  • the girdle refers to the rim (outer circumference) of the diamond. It’s primary role is to prevent chipping during the setting process.
  • the part below the girdle is what we call the pavilion. This is where all the magic actually happens; where light is reflected back through the top of the diamond to appear as fire and scintillation.

The Girdle Thickness is a Telltale Sign for Well Cut Diamonds

When you see a diamond that has a “very thin” or “extremely thin” girdle, you need to exercise extreme caution. Diamonds with very thin girdles are very susceptible to chipping during the setting process and normal daily wear.

In the example below, I had circled the portion of the diamond where the girdle thickness is going to be a major durability issue. To get a better idea of what I am talking about, do click on the corresponding links and view these diamonds under high magnification.

knife edge at marquise girdle

This particular diamond has an extremely thin – slightly thick girdle.

As I had mentioned before, the most vulnerable locations of a marquise diamond are found at its two pointed ends. In the following example, you can see that the girdle area at the tips are not thick enough to provide sufficient mechanical strength.

A slight knock at the correct angle can cause significant damage and makes this diamond a very risky purchase. And if you look closely at this particular example, you can already see that parts of the girdle has already been damaged.

damaged girdle abrasion chips marquise corner

The very thin girdle thickness at the tips makes this stone a poor choice.

Girdle Thickness Affects Spread And How Big the Diamond Faces Up

Marquises have better spread and tend to look larger than other diamond shapes with similar carat weights. If you are a smart shopper and want to get more value out of your purchase, look out for diamonds with medium to slightly thick girdles. This will help you avoid diamonds that have excess weight “trapped” within the girdle area.

uniform extremely thick marquise girdle

Why should you pay for “dead weight” that can’t be seen from a face up view?

A Real Life Comparison of Diamonds With Different Girdle Thicknesses

To give you some perspectives on size and face up appearance, let’s take a look at the following diamonds:

#1: 0.81 Carat D Color VVS2 with a thin to slightly thick girdle. It measures up at 9.42 mm * 5.19 mm * 2.97 mm (L/W/D) and has a pretty decent face-up size for its carat weight.

#2: 0.82 Carat H Color SI2 with a very thick – extremely thick girdle. In contrast, this diamond measures up at 8.67 mm * 4.72 mm * 3.20 mm.

Both diamonds weigh approximately the same and yet the 0.80 carat stone faces up significantly smaller. Here’s another comparison of 2 stones with different girdle thicknesses.

0.46 Carat D Color VVS1 with a medium to very thick girdle measures up at 8.05 mm * 4.19 mm * 2.41 mm

0.49 Carat D Color SI2 with a very thick to extremely thick girdle measures up at 7.51 mm * 3.88 mm * 2.63 mm

Again, the sizes differ significantly and the lighter diamond actually looks larger!

Now, please don’t misinterpret my intentions about maximizing spread to the extent that you start choosing diamonds with extremely or very thin girdles. A safe girdle thickness that would ensure better durability lies in the range of thin to very thick.

Why is Symmetry Especially Important in Marquises?

In my humble opinion, a diamond needs to be sparkly and be full of brilliance. However, a good diamond goes beyond that and only careful cutting can yield stones with character and enormous appeal.

By now, you should know that a marquise has the advantage of maximizes spread for its carat weight. However, this advantage comes at a price as marquises are very sensitive to symmetry details. As a result of poor cutting, a marquise can easily lose much of their wonders.

The best way to determine any issues with cut and symmetry is to see real images and videos of the diamond. offers all these features to shoppers to help you make better selections and I highly recommend them.

Here Are Some Examples of Marquises With Readily Apparent Issues…

unbalanced wings in a marquise diamond

series of flawed marquise diamonds with poor shapes

These images depict marquises with undesirable outlines and serve as a reminder to why shopping “blindly” is a bad idea. You need to understand that it is impossible to gauge the looks of a fancy shaped diamond based on its certification alone.

Sadly, I’ve seen it happened many times where eager shoppers buy solely based on a grading certificate (at sites like only to be disappointed with the outcome. It’s always a roll of the dice when you shop blindly and you won’t know what to expect until it is too late.

lop sided belly

This ugly lop-sided marquise looks more like a pear.

Where Can Symmetry Flaws Occur in a Diamond?

Symmetry flaws are basically irregularities in the diamond’s cut and can occur as a result of many reasons. More notably, the presence of inclusions and the decision to remove them often lead to intentional symmetry flaws. Furthermore, cutters are under immense pressure to polish rough diamonds for maximum weight retention and often do it at the expense of cut.

Diamonds with poor symmetry usually exhibit a wavy girdle when viewed from its profile and these problems are so blatant they can be easily noticed by the unaided eye. The main concern with such symmetry flaws is that it makes the setting process very difficult and also causes the diamond to appear out-of-shape.

wavy girdle

Notice how the red line I drawn to follow this diamond’s girdle isn’t straight? Avoid at all costs!

James Allen is hands-down the best place to shop for marquise shaped diamonds. The huge selections available and their HD magnified videos makes selecting a well cut diamond a fun and easy process. Check them out!

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