Diamond Anatomy
Diamonds don’t start out sparkling. Whether formed deep underground or grown in a lab, every diamond begins as a rough crystal that needs to be carefully cut and polished to bring out its beauty. One of the biggest factors in how much a diamond sparkles is the quality of its cut—and that comes down to its proportions, symmetry, and overall anatomy.
Diamond anatomy refers to the structural features of a finished, cut diamond. While you may not notice these parts right away, each one plays a role in how the diamond interacts with light and how it looks overall.
In this article, we’ll walk through the different parts of a round brilliant diamond—the most classic shape—and explain how its design affects the way it looks.
A Note on Facets
Before we discuss Diamond Anatomy, it’s helpful to understand what “facets” are.
Facets are the flat, polished surfaces you see on a finished diamond. They act like tiny mirrors, bouncing light within the stone and sending it back out to your eye. The way these facets are arranged—and the angles they’re cut at—has a major impact on how much a diamond sparkles.
In the round brilliant shape, there are typically 57 or 58 facets, strategically placed to maximize brightness, fire, and scintillation. These facets work together to reflect light internally before it exits the diamond, creating that signature brilliance the shape is known for.
Parts of a Round Brilliant Diamond
Table
The table is the large, flat surface at the very top of the diamond. It’s the first place light hits and the main point of entry for light to enter and exit the stone. A well-cut table helps light bounce around the inside of the diamond and return upward—adding to its brilliance and fire.
While intuitively, it may seem that a large table is favorable, balance here is key. A table that’s too large can interfere with the overall proportions of the stone (which are precisely calculated to optimize for brilliance, scintillation, and fire), and a table that’s too small can limit the amount of light that enters.
Most well-cut diamonds have a table that’s about 54% to 60% of the diamond’s width.
Crown
The crown is the upper part of the diamond that slopes down from the table to the girdle. It includes several small facets—typically bezel, star, and upper girdle facets—that work together to bend and break up light as it enters the stone. This area is where you’ll often see fire—those colorful flashes diamonds give off under the right lighting.
Crown height and angle are both important. When done right, the crown adds a balanced mix of brightness and fire. But if it’s too steep or too shallow, it can throw off how the diamond handles light, reducing its overall sparkle.
Girdle
The girdle is the thin edge that separates the top half of the diamond from the bottom. It’s also where the setting grips the diamond in the popular prong and bezel styled pieces.
While it doesn’t affect sparkle much, the girdle does matter for durability. A girdle that’s too thin can chip easily; one that’s too thick can make the diamond look smaller than it really is. At well-proportioned girdle—usually graded as “thin” to “slightly thick”—offers a good balance of protection and appearance.
Pavilion
The pavilion is the lower part of the diamond, tapering down from the girdle to the bottom tip. This is where light bounces back up through the crown and table to create brilliance.
The pavilion’s depth and angle are crucial. If it’s cut too deep or too shallow, light leaks out the bottom or sides instead of returning to your eye. A well-cut pavilion reflects light like a mirror, helping the diamond look brighter and more lively.
Culet
The culet is the small point—or sometimes tiny flat facet—at the very bottom of the diamond. Not all diamonds have a visible culet, and that’s often preferred. A very large culet can appear as a dot when you look down through the table. This is similar to the bow tie effect that’s sometimes seen in other shapes, like marquise or pear shaped diamonds.
The main reason for a culet is to prevent the point from chipping. Most modern diamonds either have no culet or a very small one that isn’t visible without magnification.
Conclusion
From the table to the culet, every part of a diamond has been specifically cut and shaped to influence how it interacts with light. A diamond with the proper proportions and structure will shine brilliantly, while one that’s cut poorly can look dull, even with high color or clarity grades.
While many shoppers focus on carat, color, or clarity, a basic understanding of a diamond’s anatomy can help give you a better sense of what really sets one stone apart from the next.
At SUNSHINE, we believe that nothing compares to seeing a diamond in person. Our GIA-certified gemologist and expert team are here to walk you through the details and help you find a stone that fits your style, your budget, and your vision.
Stop by our Philadelphia or Media location to learn more about diamond anatomy—and see the difference that expert guidance can make.
