How To Measure A Diamond (Girdle, Table, Total Depth, Crown height & Angle, Pavillion)

Do you want to find out the dimensions of your loose diamond? Knowing a diamond’s measurements can help you choose the correct ring mount size. By taking measurements, you can also determine the diamond’s carat weight.

Measuring a diamond is easy. But, you need to interpret the measurements and how they contribute to the overall size of the diamond.

This article will explain everything you need to know about how to measure a diamond. I will cover the different types of equipment you can use to get the work done, the parts of the stone you should measure, and what these measurements mean for the value of your diamond.

Equipment Used To Measure a Diamond

Diamonds are measured in millimeters. You can use three types of equipment to measure diamonds: leveridge gauge, vernier calipers, and electronic diamond gauge. Each tool has its pros and cons.

Let’s take a deeper look at these diamond measuring equipment.

Leveridge Gauge

If you are looking to measure a diamond at home, the leveridge is the handiest equipment to get the job done. This spring-loaded tool lets you measure a diamond’s dimensions by clamping the diamond in a caliper and reading the gauge for the stone’s dimensions.

Vernier Calipers

Vernier calipers are a time-tested instrument for measuring gems and are a go-to for many hobbyists. The device consists of two tongs and a slide rule for measuring the dimensions of even the smallest of diamonds. The advantage of Vernier calipers is that they are manual and don’t require power; you can carry and use the tool anywhere.

Electronic Diamond Gauge

Jewelers use technologically advanced electronic diamond gauges to take several measurements and calculate a diamond’s carat weight. Compared to the Vernier calipers and leveridge gauge, the electronic diamond gauge takes more accurate measurements. It is designed to work with all the popular diamond cuts such as round, princess, cushion, square, emerald, etc.


Unless you have different-sized diamonds to measure, you might not need a sieve. Still, these are nice-to-have little tools for a lapidary hobbyist. Jewelers use a set of circular sieves with holes punched to a specific size to sort similar-sized diamonds.

Which Parts of A Diamond Do You Need to Measure?

To get the true size of a diamond, jewelers take several measurements. You should measure each key part of a diamond to get a full picture of the size of the diamond.

Now, let us take a look at the various parts you need to consider when measuring a diamond:

Girdle Thickness

The girdle is the outer rim of the diamond. In a well-cut diamond, the girdle should be neither too thick nor too thin. You can use an American standard wire and metal gauge to measure your diamond’s girdle. This gauge is a jewelry industry standard and is easy to use.

To measure the girdle thickness, hold the diamond alongside the gauge to compare against the slots on the gauge. The gauge is marked 1 to 30 and will give a general reading of the gem’s thickness.

Table Diameter

The table is the diamond’s topmost facet. Technically, the table diameter is the distance from one end of the table to the other, and this measurement describes the size of the diamond’s top facet relative to the size of the stone. In jewelry industry jargon, the table diameter is expressed as a percentage of the girdle diameter.

Use one of the tools I have described above to measure the distance from one corner of the top facet to the other. Then, divide the table diameter by the girdle diameter and multiply the result by 100.

For example, if the diamond’s largest table diameter is 3.85mm and the average girdle diameter is 6.55mm, the table percentage would be (3.85×6.55) x100.

Total Depth

A diamond’s total depth is determined by measuring the distance between the table or topmost facet and the pointed bottom, known as the cutlet.

Using a gauge or caliper, measure the diamond vertically to determine the depth. Next, you will need to calculate the total depth, which includes the thickness of the girdle. To do this, divide the depth measurement by the average girdle diameter.

Crown Height and Angle

The crown height is the distance between the table and the girdle. The crown angle is determined by observing the inclination from the table against the star facets on the diamond’s side.

Usually, you would need to observe the diamond from the side to estimate the crown angle. A gauge or caliper can be used to measure the crown height.

Pavillion Depth

The pavilion is the bottom part of a diamond, constituting the lower diameter of the girdle, lower facets, and cutlet. The pavilion depth is part of the stone’s total depth and is calculated by measuring the distance from the girdle down to the tip of the diamond.

Which Measurements To Note For Your Diamond

Most diamond cuts require you to measure the length, width, depth, and diameter. When calculating carat weight, a depth measurement is required regardless of the shape of the diamond.

The carat weight is determined by calculating the girdle diameter and multiplying this with the depth for the classic round brilliant cut diamond. The carat weight of a princess cut diamond is calculated by multiplying the stone’s width by the length and then the vertical depth from the stone’s table to the cutlet.

For fancy cuts such as the baguette-cut diamonds and emerald-cut, the formula is the same: multiply the stone’s length, width, and depth. The length and width of a trilliant-cut diamond is measured from point to point, and the result is multiplied by the stone’s depth to determine the carat weight.

How To Measure Small Diamonds

Measuring small diamonds can be tricky and requires patience, but even a hobbyist can measure tiny gems. Use a Vanier caliper to get the job done. If you want to measure several diamonds, you will also need diamond sieves to separate stones of different sizes.

Sieve the stones and place them in different packets. Now, all you need to do is measure one diamond from each of the different packets to determine their sizes.

Extended Tips

As a lapidary hobbyist, you will want to familiarize yourself with a couple of terms when measuring a diamond. These proportions influence a diamond’s characteristics, such as brilliance and carat weight.

Understand the length to width ratio

Different diamond shapes have different length-to-width ratios. The length to width ratio is determined by dividing the stone’s length by its width. Each type of diamond shape has an ideal length-to-width ratio. A proportional diamond that appears elegant and brilliant tends to be more valuable.

The ideal length to width ratio for brilliant round cut diamonds is 1.0-1.5, while that of a pear-cut diamond is 1.45-1.75. A marquise-cut diamond’s preferred ratio is 1.85-2; the cushion cut is 1.0-1.8, emerald 1.3-1.4, and oval cut is 1.25-1.5.

Determine Depth and Table Percentage

The depth and table percentage have a big impact on a diamond’s sparkle and brilliance. Diamonds that are short with a wide table are described as shallow and have a low depth percentage. When viewed from above, such a diamond might seem large, but it will generally appear dull.

On the other hand, tall and wide diamonds have a higher depth percentage and appear more brilliant. Depending on the shape of the diamond you are measuring, each stone will have its depth percentage and its level of brilliance and sparkle.

The table percentage will also vary with the diamond shape. If your diamond has a table percentage that is too low or too high, you will notice that the stone will seem dull and might not fetch a high value.

Take Into Account the Girdle

We have already covered how you can measure your diamond’s girdle. But, what does this measurement represent? What are the implications for the value of your stone? Ideally, a diamond is more desirable when the girdle is neither too thin nor thick.

The thinner the girdle, the more prone it is to chipping and breaking, even when mounted on a ring setting. Thick girdles are no good either. When the girdle diameter is too large, i.e., the girdle is too thick, the diamond will not reflect light adequately. When this happens, your diamond might look dull and too small for its carat weight.


Measuring your diamonds can clue you into the value of the stone. Whether you are looking to turn in a profit from your stone or for sentimental value, knowing your gem’s real dimensions is something you can easily do as long as you have the right equipment. As you can see, it helps to familiarize yourself with various measurement terms; you’ll be able to interpret what these measurements mean regarding the value of your diamonds.

Sharing is caring!

Similar Posts