Anatomy Of A Diamond

Anatomy Of A Diamond

If you're shopping for a ring, necklace, pin, or another piece of jewelry, consider buying something with diamonds. These stones are beautiful, and they can make excellent investments. Before you decide what to buy, it's a good idea to learn more about the anatomy of a diamond, how to find a great diamond, and the shapes available.

The Anatomy of a Diamond

To grade the cut of a diamond and its overall quality, the Gemological Institute of America or GIA makes a variety of measurements:


The table is the horizontal top facet of the diamond, and the table size is its diameter. The GIA records it as a percentage of the diameter of a diamond at its widest point.


The culet is a small facet on the bottom of a diamond that helps prevent chipping or abrasion, and the GIA rates its size as none, very small, small, medium, slightly large, large, very large, or extremely large. The best diamonds have no cutlet or one that's not visible to the naked eye.

Total Depth

The total depth is the distance from the table, or horizontal top facet, to the culet, and it's a percentage of the diamond's diameter.


The girdle thickness measures the average thickness of a diamond's edge at its widest point, where a setting usually secures it. A girdle that's too thick could make the diamond look smaller than similarly sized stones, and one that's too thin may make chipping or other damage more likely.


The pavilion is the lower part of a diamond that's below the bottom edge of the girdle. The pavilion depth is usually recorded as a percentage of the average girdle diameter. If it's too shallow or deep, it won't direct as much light upward. Diamonds with ideal pavilion depths reflect more light for better brilliance. The pavilion angle is important for a diamond's brightness as well. It's the average of the angles formed by the pavilion's main facets and the girdle. The best diamonds have pavilion angles between 40.6 and 41.8 degrees.


The crown height is the vertical distance from the top edge of the girdle to the table, and it's a percentage of the average girdle diameter. The crown angle is the average angle that a diamond's facets form at the top edges of the girdle, and it's usually from 31.5 to 36.5 degrees for the best diamonds.


The star length is the average horizontal distance from the table to the points on a diamond's star facets, the ones above the girdle that touch the edges of the table. It's a percentage of the horizontal distance between the edge of the table and the girdle. The best diamonds usually have star lengths between 40% and 70%.

Half Facet or Lower Girdle Facet 

The half or lower girdle facets are the ones directly below the girdle. The half or lower girdle facet length is the average vertical distance between the girdle and the points of the facets. The GIA records it as a percentage of the pavilion depth, and the best diamonds have lower girdle facets between 65% and 90%.

Finding the Best Diamond

When you're searching for the best diamond for your budget, you should keep these characteristics in mind. However, the overall cut and the look of the gem you choose are more important than any particular measurement. The GIA evaluates the brightness, fire, and scintillation of each diamond. 

Brightness is how the diamond reflects white light, and fire is how the diamond disperses white light. Diamonds with high fire act as prisms, reflecting light with many different colors. Scintillation is how much sparkle a diamond has.

You should also consider a diamond's weight compared to its diameter, its symmetry, and the quality of the polish along with whether any defects are visible with the naked eye or magnification. Clarity is the amount of inclusions or flaws in the diamond, and the best diamonds are rated FL, or flawless. You can save money by choosing a diamond that looks flawless to the naked eye but still has some microscopic inclusions.

Diamonds can come in almost any color, and the GIA color scale covers most diamonds. It starts with D, which is colorless, and ends with Z, which is light yellow or brown. The best diamonds are usually colorless, but some of the most expensive diamonds in the world are bright yellow, blue, or pink.

Diamond Shapes

The shape of a diamond impacts its cost and quality as well. The best diamonds usually have a round cut, also called a brilliant or ideal cut. You can choose from a variety of other shapes as well. Princess cut diamonds are square, and they look as brilliant as a round cut. They're also less expensive because less of the diamond is discarded during cutting. A cushion cut or pillow cut is similar to a princess cut, but it has more rounded edges. It looks slightly smaller than a round-cut diamond the same size, but it has excellent fire.

Oval and teardrop or pear-shaped diamonds have tables or upper surfaces with larger areas, making them look bigger. However, the point on tear-shaped diamonds makes them more prone to chipping. Marquise diamonds have curved sides and two tapered points. They're more likely to chip than teardrop or other diamonds because of their points, but they look bigger than any other diamond shape. They also cost less than round diamonds. However, oval, pear-shaped, and marquise diamonds refract light to form a bowtie pattern in the middle that some people don't like.

A rectangular or emerald cut looks more subtle, and the facets are arranged in step-like patterns that resemble a hall of mirrors. Since even a more shallow stone still looks attractive, you can choose a lighter stone with a large table that makes it look bigger. With a ring, an elongated diamond shape can make your fingers look longer.

Contact us at Martin Busch Jewelers for help choosing a beautiful diamond or creating a custom piece. We can also buy your existing jewelry or help you reset it.