Traditionally emerald green should be the perfect balance of blue and yellow – a pure green hue. The appraisal and appreciation of colour is, of course, subjective to some extent. Emeralds from different origins often have distinctive colours although each deposit can have a range in hues.
A gemstone’s clarity has to do with the number of inclusions that it contains, the size of those inclusions and their position within the gemstone. The fewer, smaller and less conspicuous the inclusions, the better. It is, however, extremely unusual to find a “clean” emerald. Almost all contain imperfections, known as jardins (French for gardens), which are visible to the naked eye.
Emerald is a relatively hard gemstone – about 7.5 or 8 on the industry-standard Mohs scale, yet it is also brittle, and this, together with the presence of jardins, can make it a challenging gemstone to cut. If an emerald is well cut, it will mask colour variation, inclusions and other imperfections, and not create “extinctions” (dark patches). The gemstone should be well proportioned and symmetrical, with no distortions. It should have sharp facet edges and flat faces – reflections should enter the eye at once, not “roll” across the face – and the gemstone should be free of chips and scratches.
Carat weight obviously helps determine the price of the emerald, and a 4 carat stone will be more expensive than a 1 carat stone, all other factors being equal. But carat weight plays a much larger role in the pricing of diamonds than it does with emeralds. With the latter, we are primarily interested in the color of the stone, then its clarity and cut, and only finally its carat weight.
Emerald experts agree that it’s better to buy a smaller emerald with excellent color quality than a larger one with poor color quality.