Diamond Cut

What are the parts of a diamond?  How does cut influence diamond prices?

Cut's Influence on Diamond Prices

Below are the lowest priced diamonds from three popular retailers when all factors are equal (round, 1-carat, H-color, VS2-clarity) except the cut grade.  The lowest cut grade, "poor," was not included as diamonds of that grade are usually not worn as gemstones.

Notice that for the first retailer, the prices vary a total of less than $240 across the cut grade categories.  In fact, there is no price difference between the lower two cut grades, "good," and "fair."  Similarly, the second retailer has no price difference between the higher two cut grades.  (The $5,020 price point could be an erroneous price.)  Even for the third retailer, the drop from "ideal" to "good" cut grade only saves $500. 

This information shows that cut grade is not a large influence on a diamond's price.  Therefore, a buyer should not be shy about upgrading from a low cut grade to higher cut grades.  It is a more affordable upgrade than a visible difference in carat weight.  So, rather than wonder which is more important--size or quality--the pricing here suggests you can buy an ideal cut diamond without sacrificing size. 

What are the diamond's point, polish, symmetry, girdle, culet, pavilion, crown, depth, table, and diameter?

I found a nice image explaining these terms online but can't figure out how to load it on this site.  So, please take a look at the image of a diamond's culet, girdle, pavilion, crown, table, diameter, and depth. 

In addition, The polish grade describes the smoothness of the diamond’s facets. Poor polish of the diamond surface can dull the light radiating from the stone. It may also create blurred or dulled sparkle.

The symmetry grade refers to alignment of the facets in relation to each other.  Poor symmetry can misdirect the light inside the stone as it enters and exits the diamond – the more light is lost due to poor symmetry, the less sparkly the stone would look and the more dark spots you can observe when looking at the diamond from the top.