Diamondsking Guides - the Structure of the Diamond

The diamonds can be divided in three main parts, the crown corresponding to the top side of the stone, the pavilion being the lower one, and the girdle joining them.

The Crown

The crown const of the upper side of the diamond, we can easily spot the table, which is the top of the stone, covering a large flat area, it‘s highlighted in red color in the scheme at the right of this text, we can find as well three different facet types, the star facet which correspond to the blue color, the bezel facet being the green, and the upper girdle facets, in yellow.

As the diamonds catch the light, the work of the crown is to divide the light entering the diamond into white light, which gives the gem its brightness.

The size of the table, (as a % of the crown), determines the amount of white light and brilliance that the diamond is going to reflect. Having a well proportionate table is of great importance for the diamond, usually the range for an ideal sized table would be 53-60% of the crown surface, a 61-65% would still be acceptable, but more than that would make the diamond look blurry or misty.

Other aspect to mention about the crown is its angle, this should be ranging between the 32 to 35 degrees, if it’s smaller, will make the table surface too big, (read above to understand what this causes), and if it’s bigger, will have in consequence a “shrink” effect on the diamond, and it will look smaller than it really is… I bet that no one wants that!

The Girdle

The girdle correspond to the middle area of the diamond, the thin, it is an unpolished band around the widest part of the diameter of the gem. Its purpose is to protect the border of the stone from being chipped (even when we already learnt that the diamond is the hardest material on Earth, it still can be damaged!).

We should avoid diamonds with thin girdles, or one that is too wide, the middle term (as in most of the things!) is the best way to go.

We can apply the logic here, if the girdle is too thin, it doesn't give enough protection. On the other side, if it's too wide, does protect against the chipping, but it is not really esthetic (nice looking).

Now the question is: How do I know if the girdle is too thin or too wide?

You must observe the stone from the side. If it looks like there is a white colored stripe around the center of the gem, the girdle is too wide. If you are not able to see it at all with naked eye, look at the same part of the stone with a 10X lens. If again you cannot see at all the girdle with it, it's way too thin.

The Pavilion

The pavilion can be considered as the key for the diamond to shine, its work is to reflect the light that passes through the crown back to our eyes.

The light enters the diamond through the crown, is divided into white and colored light, spring back off the facets of the pavilion back up through the crown, and there we can appreciate the sparkle. But in order to maximize this effect, the gem must have a proportionate cut, and be well polished.
The process is the following: The light enters the gem from the table and the crown’s facets, pass through the diamond, and is reflected back by the facets of the pavilion. (See scheme).

For all this process to be ideal, the angle of the pavilion should meet certain degree range, depending on the shape of the gem, it varies. For the Round Brilliant, the perfect angle is between 40 and 41.5 degrees. On the other side, for the Marquise, pear, and ovals, the ideal angle would be 40 degrees. For emerald and rectangular cuts, perfect would be 45.05 degrees. If the pavilion angle is not proper, it will not reflect the light effectively, and the diamond will not have the sparkle that we would expect.

Now, finding a perfect pavilion angle can be somewhat complicated.

Which are the acceptable pavillion error grade ranges?

In a round diamond, the sparkle diminishes very much if the angle error is even a tenth of a degree above or below the ideal range. In marquise, oval, or pear, this error range can be more flexible, still being really good with three-fourths of a degree with only a 10% loss of sparkle. Emerald and rectangular cut diamonds have the widest error range variance of 1.75 degrees. Each extreme will also cause a 10% sparkle loss.

Hope this guide helped you to understand more about the fascinating world of the diamonds. Visit us at DiamondsKing for more information !