Coloured gemstones are generally cut to maximise the beauty of their colour. To recognise quality in the cut of a gemstone, there are several points to consider.
What to Look For
A good cut showcases the gemstone's colour, diminishes its inclusions, and exhibits good overall symmetry and proportion. Because gemstone colour can vary, there are no hard geometrical standards when it comes to maximizing brilliance or colour. Gemstones, especially rarer ones, are sometimes cut for size without regard for their colour. For example, when corundum varieties such as sapphire and ruby are cut for maximum weight rather than beauty, they may display banded colours or streaks. Blue Nile sells only the finest quality, hand-selected coloured gemstones.
Buyer's Tips: In a gemstone with more saturated colour, the best cut may be more shallow than average, permitting more light to penetrate the gemstone, while in a less saturated gem, the colour may benefit from a deeper cut.
Look at the gemstone in the setting and ensure that all the facets are symmetrical. An asymmetrically-cut crown indicates a gemstone of low-quality. In all cases, a well-cut gemstone is symmetrical and reflects light evenly across the surface, and the polish is smooth, without any nicks or scratches. These are the characteristics that Blue Nile jewellers look for when selecting our gemstone jewellery.
Buyer's Tips: Like diamonds, fine quality colour gems usually have a table, crown, girdle, pavilion, and culet. Irridescent opals are one exception, and most often have a rounded cabochon cut.