Diamond Crown Angle: A Cut Element Not to Overlook

Diameter – The width of a diamond as measured through its girdle.

Table – The largest facet of a diamond usually occurs at the top of the stone.

Culet – The facet at the bottom tip of a diamond. The ideal culet is never visible to the naked eye and is often graded as Small or None.

Depth – The height of a diamond from its culet to the table.

Girdle – The narrow band around the widest part of a diamond.

Pavilion – The bottom part of a diamond, from the girdle to the culet.

Crown – The top part of a diamond, from the girdle to the table.

Check our ideal diamond proportions for each shape as a reference.

Excellent vs. Super Ideal Round Proportions

As already shed light upon, a diamond crown is a portion that spans across the table towards the girdle of the stone. It has been so aptly named that if you were to view the structure from the top, the diamond crown would look exactly like an actual crown placed upside down.

The crown of a diamond plays a crucial role in influencing the light performance of the diamond: this is so because it’s the part that handles the largest amount of light entering or leaving the stone. You can look at the crown, along with the table, as the window of a diamond.

The crown has two fundamental aspects that determine the fire and brilliance of a diamond - crown height and angle.

A diamond’s crown height refers to the linear distance between the table and the girdle. After it is determined, you express it in relation to the girdle diameter of the diamond. Usually, the average crown height is expressed to the nearest 0.5%.

On the other hand, the crown angle of a diamond refers to the angle bound by the bezel facet of the diamond and the girdle. The crown angle is the most significant factor that influences how light enters the crown and, subsequently, how the entire structure of the diamond handles that light.

A shallow crown angle makes the crown appear flatter, reducing light penetration and increasing light leakage. The net effect diminishes the sparkle and brightness of the stone.

Similarly, an overly deep crown angle makes the crown appear dull, adversely affecting the light-handling performance of the stone - this accentuates the importance of selecting a diamond with an ideal crown angle.

Besides allowing light into and out of a diamond, the crown angle determines how light travels to the pavilion. As soon as light strikes the diamond at the angle, it is refracted so that it can travel down to the pavilion.

Lastly, through the crown angle, light is dispersed into different colors and hues, which impacts a diamond’s scintillation.

To calculate the crown angle, we need to determine the crown depth, the diamond’s table, and the pavilion angle. All of these units should be expressed as percentages of the average diameter of the diamond.

Calculating the Pavilion Angle of a Diamond

1. Determine the pavilion depth of the diamond and enter your answer in a scientific calculator
2. Divide the answer by 50
3. Check for your calculator’s Tan – 1 button; this symbol usually appears in small letters above the Tan button. In some calculators, however, you may need to press and hold the Shift button as you press the Tan key. The answer that you get is the actual pavilion angle expressed in degrees.

Calculating the Crown Angle of a Diamond

1. Divide the table of the diamond by 100
2. Subtract your answer from 1
3. Multiply the answer by 50
4. Divide the crown depth by your answer above
5. On your calculator, press the Tan – 1 button. The answer that you get is the actual crown angle expressed in degrees.

The above formula only applies to round brilliant cut diamonds that do not contain culets. If the diamond concerned has a culet, you would be required to use the crown angle formula to calculate the pavilion angle. As you do, you’ll now factor in culet as opposed to the table.

When determining the ideal crown angle, the general formula is that the higher the diamond crown, the greater its crown angle. As you shall observe, most diamonds have crown angles ranging from 25° to 35°.

The diamond may look brighter if the crown angle is shallower than 25°. However, such stones are more prone to chipping than those with higher crown angles. You may need to set diamonds with shallower crown angles in mountings that protect the girdle area to prevent damage. A perfect setting for such diamonds is the bezel setting. Alternatively, you may consider other mounting options where the diamond is less susceptible to damage; examples include pendants and earrings.

On the other hand, diamonds with higher crown angles are considered stronger and less prone to chipping. Such stones are excellent both in jewelry and as loose diamonds. But one notable drawback to steeper crown angles is that they make the diamond look unsmooth, adversely impacting its fire and brilliance.

You must first contemplate the diamond’s pavilion angle to arrive at the ideal crown angle. Ideal pavilion angles usually range from 40.6 to 41 degrees - this is the range within which a diamond handles light optimally. Shallower crown angles should correspond with steeper pavilion angles and vice versa.

As for the crown angle, always insist on an angle closer to 34° if you’re looking for more brilliance and an angle closer to 35° if more fire is what you are seeking. Based on the relationship between crown angles and pavilion angles, the crown angle of 34° will be ideal if you match it with a steeper pavilion angle, say, 41°.

Calculating a diamond’s crown angle isn’t a walk in the park. Nonetheless, you must understand how to go about it before buying a diamond because the fire and brilliance of the stone depend on its crown angle.