The beauty and desirability of diamonds comes from their eye-catching sparkle, achieved by careful handling by an expert artisan. A gemstone that does not glisten is hardly deserving of such a name, so precisely what makes a diamond sparkle?
It is the diamond cut which determines how the stone reflects light, and therefore give a truly brilliant sparkle. Known in the industry as ‘fire’, referring to the coloured light reflected, and ‘brilliance’ for the uncoloured light, optimum levels of sparkle can be achieved only through a supremely executed cut.
Perfecting brilliance: the best diamond cut
Though diamond cutting can be traced back to the Middle Ages, it wasn't until the late 1400s that the importance of total symmetry to reflect light was realised, and the development of tools to cut them improved. Not until the 1900s was a diamond cut so well it sparkled in the way we expect today.
It was mathematician and engineer Marcel Tolkowsky, coming from a family of jewellers, who crafted a near perfect cut. With 57 facets positioned at 45-degree angles, it created brilliance and fire, and the greatest sparkle, setting the standard for all future diamond cuts.
Today, with the aid of precision tools like lasers, cutting diamonds is easier, quicker, and with an endless choice of shapes and cuts. However, old rules apply. If cut too shallow, light reflects beneath; too deep and the stone reflects sideways. For example, the best cut for a dazzling engagement ring will result in the highest percentage return of white light and the ring will sparkle from the front, known as the crown, regardless of how light hits it.
Different diamond cuts: price and preference
A cutter chooses the shape and cut of each diamond based on its original rough shape. Their task is to maintain its carat weight (avoiding wastage) while creating the best possible sparkle. Even with the best tools, creating the perfect cut isn't easy, thus why diamonds differ in quality and price. Two of the same shape, colour, clarity and carat diamond can have a 40% price difference due to cut. More sparkle often means more money, however some people care more about weight and size rather than cut, ultimately it comes down to price and preference.
As a quick guide, below are the commonly used different diamond cuts with their ability to reflect light and provide sparkle given in percentages.
We'll class the round brilliant cut at 100%, but no diamond is realistically so perfect. Favoured in engagement rings and jewellery where the gemstone is given centre stage.
Oval cuts seek to mimic the same brilliance and fire created by a round cut, with the added benefit of appearing larger due to its length. Sparkle is around 90%.
Of similar levels is the pear cut, where its rounded edge preserves the high levels of sparkle.
Heart cuts give approximately 80% sparkle and create a unique statement piece where this high level of brilliance is crucial.
The princess cut will give 70% sparkle and lose the rounded shape that provides the highest levels of brilliance, however, its large crown can give the illusion of a greater size.
Cushion cut diamonds provide 60% sparkle and give a distinctive light pattern due to their mix of rounded and straight edges.
60% sparkle is provided by emerald cut diamonds which give less fire but a unique type of sparkle which interplays the light and dark planes of the step-cut stone.
The baguette cut will give 45% sparkle and is similar to an emerald cut without the rounded edges, as such, this removes the potential for sparkle that smoothed edges provide.
Choosing the best cut you can afford is the best way to ensure you achieve the most sparkle for your money, though personal preference may mean your desired shape equals less sparkle.