When choosing diamond jewellery, one of the most important aspects to consider is the quality of cut of the gemstone. This, even more than the colour and the clarity of the diamond, determines the amount of sparkle coming from the gem. A well cut diamond will have well proportioned and well angled facets which precisely reflect and refract the light whilst preventing any from prematurely escaping through the back of the gemstone.
In a finished diamond, the widest part of the diamond is called the girdle. The section below is known as the pavillion and the section above the girdle is called the crown. A diamond is held in a setting by its girdle. The crown is that part of the gemstone which is easily visible in the ring. The very top of the crown is the table.
The table is the largest and most important facet of the whole cutting process because it's the main entry point for light passing into the gemstone and it's also the facet which lets out the most fire and sparkle. In a Round Brilliant cut diamond, the table is ideally 56% of the width of the girdle but this proportion can increase dramatically up to a massive 90% in the mirror cut.
In table cut diamonds, the table facet is shaped into a geometric square or square like shape, such as a rectangle. This is unusual because the table facet of most cuts is round, oblong, octagon as so on. Even square shaped Princess cut gemstones have octogonal table facets and the square like Cushion cut, a rounded square table.
However, even the geometric table facets of the true Square cut and Baguette cut, themselves based on the Oblong cut aren't enough to make them true Table Diamonds. This is because they're based on a step cut, where the facets along the pavillion are cut into steps parallel to the edges much like the sides of a Pyramid.
The sides of true Table Diamonds are cut into gently rounding facets not steps. This helps maximise the sparkle of the gemstone.
The Table cut is actually an old fashioned cut. Brooches, earrings, pendants and rings dating from the 17th and 18th centuries often contain Table cut gemstones because this cut was fashionable at that time.
These days, precision methods of cutting using computer aided technology have produced many different diamond cuts all with their own particular beauty.