Diamond Cut

The cut is perhaps the most important of the four Cs, so it is important to understand how this quality affects a diamond's properties and value. 

Any diamond's angles and finish determine its ability to handle light. A good cut gives a diamond brilliance (the brightness that seems to come from the very heart of the diamond), scintillation, and dispersion (the sparks of color that seem to leap out from the diamond's surface when the diamond is tilted back and forth). Don't confuse Cut with Shape. Cut refers to how well the cutter has designed and proportioned the diamond. As you can see in the images below, when a diamond is well cut, light entering through the table travels deep into the pavilion. Once light reaches the pavilion, it bounces back and forth on the mirror-like inside walls, multiplying in brightness and intensity before reflecting out of the diamond through the table and into the observer's eye.

To understand how the pavilion makes a diamond so brilliant, think of an empty room with a single candle as its only light source. If you add a mirror to the room, it reflects the candle's image, creating a second image of the flame and doubling the room's light. Add more mirrors to the room. The room's brightness will increase the original candle flame. A well-cut diamond works in much the same way as a series of mirrors that multiply the original light source's brilliance. This light is the brilliance we mentioned, and it's what makes diamonds so mesmerizing.

However, when a diamond is poorly cut (either too shallow or too deep), the light that enters through the table reaches the pavilion facets at the wrong angle and fails to be intensified and reflected properly; it 'leaks' out from the sides or bottom of the diamond rather than reflecting through the table to the eye. Less light reflected to the eye means less brilliance, the most important factor in a diamond.

Diameter: The width of the diamond through the girdle.
Table: The largest facet at the top.
Crown: The top part from the girdle to the table.
Girdle: The narrow band around the widest part of a diamond.
Pavilion: The bottom part from the girdle to the culet.
Culet: The facet at the bottom tip. The preferred culet is not visible to the naked eye (graded "small" or "none").
Depth: The height from the culet to the table.
 

Shallow-Cut	Fine -Cut	Ideal-Cut	Deep-Cut

The first step to choosing a diamond is selecting from one of the major diamond shapes available. This step in the diamond-buying process is one of the easiest and depends entirely on personal preference. Round brilliant stones are the most popular and quintessential diamond shape. Don't confuse a diamond shape with a diamond cut. One shape is not necessarily better than another. The cut can range from ideal to poor for each shape, meaning light refraction and dispersion can also range from ideal to poor.