Of the diamonds mined only 20-25% is gem-quality diamonds usable for ornaments. But even they require modification to certain extent.
The art of shaping and polishing a diamond from its crude form of a rough stone to its final gem proportions is referred to as Diamond Cutting. A diamond cut is a style or design guide used while shaping a diamond. The Cut does not refer to shape (pear, oval), but the symmetry, proportioning and polish of a diamond. The cut enhances the diamond's ability to reflect back the light effectively to make it appear brighter.
Factors Influenced by Diamond Cut:
Brilliance: Brilliance refers to the white light reflections from the external and internal facet surfaces of a diamond. When light hits the diamond's surface, some light enters it and is reflected back. The most immediate light reflected back is returned by the crown's angles.
Scintillation: Scintillation refers to the small flashes or sparkles of light that are seen when the diamond, light source or the viewer is moved. The light that isn't immediately reflected back enters the diamond and reflects from the inside walls toward the centre of the diamond. This light, which bounces off the internal walls of diamond, is the quality described as scintillation.
Fire: Fire refers to the spectral colours which are produced as a result of the diamond dispersing the white light. Once the light is bounced off the inside walls towards the centre of the diamond, it then shoots back through the top of the diamond. Because the light is slightly bent by the diamond, a colour spectrum is visible when light exits the top of the diamond.
Anatomy of a Diamond:
To have proper understanding about a diamond's cut, it is necessary to understand the terminology of basic diamond structure.
- Diameter:The width of a polished diamond from one side of the girdle to another is referred to as the diameter.
- Table:The flat facet on the top of the diamond. It is the largest facet on a cut diamond.
- Crown : The crown refers to the top part of the diamond measured from the surface of the table upto the girdle.
- Girdle: The widest edge of the diamond where the crown ends and meets the pavilion is called girdle.
- Pavilion: The pavilion is that portion of a diamond that that begins at the girdle and extends downward to the point of the culet. It is the bottom part of the diamond.
- Culet: Culet is the tiny flat facet at the bottom tip of the diamond. It is the diamond's smallest facet.
- Depth: The total length of a diamond, measured from the culet to the table is referred to as the depth of a diamond.
After having understood the basic terminology about the structure of a diamond, here's a quick glance into the various grades of the Diamond Cut. The cut grade is determined based on light performance, proportion and final finished features of a diamond. Based on these factors, the grades are:
- Ideal/ Excellent (EX): The light performance is excellent. The light entering the diamond is reflected back to the maximum. A diamond with this cut will be extremely beautiful and rare.
- Very Good (VG): It has very good light performance. It reflects back almost all of the light that enters the diamond. Diamonds with Very Good cuts are of outstanding value.
- Good: Diamonds with ‘Good' cut have good light performance. They reflect most of the light that enters but less than diamonds with ‘Very Good' cut. Good diamond cuts are far less priced than Very Good cuts.
- Fair: These diamonds are not as brilliant as diamonds of Good cuts or above grade but still are considered as good quality diamonds.
- Poor: Diamonds cut either too shallow or too deep causing much of the light to leak out of the diamond's sides and base are categorised as ‘Poor' cut diamonds.