The 4Cs: Clarity, Colour, Cut and Carat Weight
Diamonds come in many colours. Those ranging from colourless to light yellow and brown fall within the normal colour range. Within that range, colourless diamonds are the most valuable and set the standard for grading and pricing.
Clarity characteristics refer to diamond’s internal features, called inclusions, and surface irregularities, called blemishes. Clarity is the relative absence of inclusions and blemishes. Flawless diamonds are very rare and command top prices.
Cut refers to the proportions, symmetry and polish that effects how a diamond’s facets interact with light. Diamonds with different proportions and good polish make better use of the light, and will be bright, colourful and scintillating.
The term “cut” can also describe a fashioned diamond’s shape. Shapes other than the standard round brilliant are called fancy cuts. The best known are the marquise, princess, pear, oval, heart and emerald.
Diamond size is measured by weight in terms of metric carats. One carat is two-tenths (0.2) of a gram. Diamonds are weighed to a thousandth (0.001) of a carat and then rounded to the nearest hundredth, or point. Fractions of a carat can mean price differences of hundreds – even thousands – of dollars, depending on diamond quality.
Large diamonds are rarer than small diamonds. So although a 1-carat diamond weighs the same as four 0.25-carat diamonds, if all the other quality factors are equal, the larger diamond is worth much more than the sum of the four smaller diamonds.
Many diamonds emit a visible light called fluorescence when they’re exposed to ultraviolet (UV) radiation. Blue is the most common fluorescent colour in gem-quality diamonds. In rare instances, fluorescence can be white, yellow, orange or other colours. Strong blue fluorescence can make a light yellow diamond look closer to colourless in sunlight. If the fluorescence is too strong it can make the stone look cloudy or “oily,” which can lower the value of the diamond.
How to Care for Diamonds
Diamonds are the hardest material on earth – 58 times harder than anything else in nature – but any stone, including a diamond, will break if it’s hit hard enough in the right place.
Warm water and mild soap with a toothbrush is a safe way to clean diamond jewellery. Diamonds can also be safely cleaned with lint-free cloths and commercial jewellery cleaning solutions.