This guide defines the five essential characteristics of gemstone quality. By understanding these characteristics, you'll be able to shop with confidence. Print this helpful information and take it with you shopping so you can make the best choice on a beautiful piece of gemstone jewellery.
The jewellery industry recognizes the highest quality gemstones by purity of their hue, the depth of tone, and the colour saturation. The best value is in colours that include "slight" traces of other colours, are not too light or dark, and have a lot of saturated colour. Blue Nile offers some of the highest-quality coloured gemstones available. Nearly all gemstones today, including Blue Nile stones, have been treated to enhance their colour. The most common methods of treatment are heating, nearly always seen with aquamarine, citrine, amethyst, sapphire, ruby and tanzanite, bleaching commonly seen with pearls, and irradiation performed on nearly all blue topaz.
Almost all gemstones contain inclusions. Even those most highly prized have at least some inclusions. Flawless gemstones are very rare and very expensive. The best value is found in gems that are lightly to moderately included, like those in Blue Nile gemstone jewellery. Emeralds are typically treated with colourless oil, wax or resin to minimise surface-reaching inclusions.
Unlike diamonds, with gemstones there isn't an "ideal" cut geometrically configured for maximum brilliance. But a high-quality gemstone cut is one that presents the most even colour, exposes the fewest inclusions, and displays the majority of the gemstone weight when set in jewellery.
The carat weight of a gemstone is not necessarily an accurate gauge for gemstone size. To help you judge the size of a gemstone, Blue Nile lists the diameter of the gemstone when viewed from above - since if the gemstone is set in jewellery; this is the only part of the gemstone that is visible
Nearly all gemstones on the market, including gemstones offered by Blue Nile, have been treated to enhance their appearance. Gemstones that have not been treated but exhibit desirable colour and clarity command extravagant prices. Some enhancement treatments are almost universal, are permanent, and require no special care of the gemstone, such as heat treatment to enhance colour. Other treatments are common, and may require more or less special care to avoid damage, such as infusion of colourless oil, wax or resin to improve clarity.