Crown (gemstone)
The upper part of a faceted gemstone, from the girdle up to the table.
Crown facets
A round brilliant crown has 33 facets including the table, made up of star facets, bezel facets and upper girdle facets. The angle of these facets decides how light is split and spread as it leaves the stone.
Crown angle and height
Crown angle is measured between the bezel facets and the girdle plane. Round brilliants with strong performance often sit around 34 to 35 degrees, but a good result depends on how the crown and pavilion angles work together. A steeper crown tends to increase fire, while a shallow crown can make a stone look bigger face up but reduces it.
Crown height, the distance from girdle to table as a percentage of the diameter, follows from the crown angle and the table size.
Crowns in CAD and renders
In jewelry CAD, stones usually come from a library with standard proportions, which is fine for most work. For a high value centre stone, use the real measurements from its grading report when you can, especially the crown angle and total depth, because the render should match what the customer receives.
The crown also changes how the stone sits in its setting. Prongs grip just above the girdle, so the crown height decides how much of each prong tip shows. In close-up renders, a crown that is too low makes prongs look oversized.