1. CUT (POTONGAN)
Diamond cut is perhaps the most important of the four Cs, so it is important to understand how this quality affects the properties and values of a diamond. A good cut gives a diamond its brilliance, which is that brightness that seems to come from the very heart of a diamond. The angles and nish of any diamond are what determine its ability to handle light, which leads to brilliance.
The techniques for cutting diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky.
Tolkowsky defined the ideal dimensions as:
- Table percentage (table diameter divided by overall diameter) = 53%
- Dept percentage (overall depth divided by the overall diameter) = 59.3%
- Pavilion Angle (angle between the girdle and the pavilion) = 40.75%
- Crown Angle (angle between the girdle and the crown) = 34.5%
- Pavilion Depth (depth of pavilion divided by overall diameter) = 43.1%
- Crown Depth (depth of crown divided by crown diameter) = 16.2%
The culet is the tiny point or facet at the bottom of the diamond. This should be a negligible diameter, otherwise light leaks out of the bottom. Tolkowsky’s ideal dimensions did not include a culet. However, a thin culet is required in reality in order to prevent the diamond from easily chipping in the setting. A normal culet should be about 1% – 2% of the overall diameter.
The width of the diamond as measured through the girdle.
This is the large, at top facet of a diamond. Crown The upper portion of a cut gemstone, above the girdle.
The narrow rim of a diamond that separates the crown from the pavilion. It is the largest diameter to any part of the stone.
The lower portion of the diamond, below the girdle. It is sometimes referred to as the base.
The tiny facet on the pointed bottom of the pavilion, which is the portion of a cut gem below the girdle.
The height of a gemstone, from the culet to the table.