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Stars in your eyes | Emerald

2016-07-29

Stars in your eyes|Emerald

 
 
No stone has a colour that is more delightful to the eye, there being no green in existence more intense than this.
——Pliny the Elder, wrote in the first century AD
 
       The romance surrounding emeralds centres on the stories and the people who have adored them since they were first discovered in Egypt, which records show was at least 4,000 years ago. Cleopatra loved emeralds so much so that the first emerald mines in Egypt were named after her, and she would present foreign statesmen with emeralds carved in her likeness as a symbol of her power. The Incas filled their temples with emeralds as the priests believed that their goddess loved emeralds above all else. The Mughals associated the green of the emerald with paradise and it is also the official colour of Islam. Given such associations, fine emeralds became one of the most desirable trade commodities throughout vast stretches of the world.
 Zambian emeralds range in colour from bright green with yellowish undertones to a vibrant green with bluish undertones. They compare favourably with the famous Muzo emeralds of Colombia — and generally contain fewer inclusions.

 

Colour

       Green, naturally. Vivid green, preferably, with lots of depth. Neither too dark nor too pale, and evenly distributed throughout the gemstone. 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. Zambian emeralds, for instance, often have distinctive secondary hues of blue, which can be utterly mesmerising.

 

Clarity

       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 inclusions that are visible to the naked eye. These may be embedded crystals of other minerals, growth lines, cleavages or tiny fractures. They are entirely natural. They are, indeed, a kind of code – one that can reveal the story of the gemstone’s origin and its subsequent migration from subterranean darkness to the light of day. As such they may be thought to possess their own kind of beauty – some of their patterns are so intricate they are referred to as an emerald’s ‘jardin’.

       Inclusions: The clarity of a gemstone is determined by the number, size and location of inclusions which are present in the gemstone. They reflect its fascinating geological aspects. Internally and externally too, there may be the presence of fissures, fractures and cavities which affect clarity. View Fullscreen

       Transparency refers to the ability of a gemstone to transmit light. It is affected by the quantity or absence of opacity and brilliance present in the gemstone. View Fullscreen

 

Cut

       Emerald is a relatively hard gemstone – about 7.5 or 8 on the industry-standard Mohs scale, where talc is 1 and diamond is 10. Yet it is also brittle, and this, together with the presence of jardins, can make it a challenging gemstone to cut. The so-called emerald cut – rectangular or square, with bevelled edges – was specially developed to show emeralds off to best advantage while minimising the risk of fracturing or chipping. However, emeralds are also available in cushion, oval and pear cuts. Recently the smooth, dome-shaped cabochon cut has become popular, as have non-traditional slices and rough cuts.

       If an emerald is well cut, it will mask colour variation, inclusions and other imperfections, and not create “extinctions” (dark patches). Badly cut gemstones tend to maximise weight at the expense of brilliance. Indeed, badly cut gemstones tend to be bad gemstones in the first place – they are not worth the time it takes to cut them well. By contrast, a high-quality gemstone will almost always be well cut.
       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. When polished well the gemstone should also possess good lustre – in the case of emerald, the desired quality is known as “vitreous”.
       With emeralds, beware of vulnerable-looking corners. Because emerald is relatively brittle, it is preferable, from a practical point of view, to choose an emerald cut over other traditional cuts, since it reduces the likelihood of damage to the gemstone.

 

Treatments

       Emeralds are nearly always oiled to enhance their colour and mask inclusions, and there is nothing untoward about this centuries-old process. It does no damage to the gemstone and its effects are not permanent – the oil will dry out eventually. The presence of oil may be revealed in a slight iridescence on the surface of the gemstone or one that may be seen inside the gemstone when viewed under a bright light – though iridescence within an emerald can also occur naturally. 
Check for concentrations of dye in any cracks in the gemstone – dye is used to improve inconsistent or weak colour.
       Emeralds with significant fissures are sometimes filled with a resin or polymer to improve clarity. If so, flashes of orange or blue may be noticed when the gemstone is inspected under a bright light – to an experienced eye, they are fairly easy to spot. It is important to know about fillings, as they can be dislodged during setting or cleaning.
       The presence of joining lines along the edges could reveal a “composite” emerald. If in doubt, put the gemstone in water – you will see a distinct line at the join.
The extent to which an emerald has been treated will affect its value – an emerald with good natural colour and clarity will always be more valuable than one whose qualities have been artificially enhanced. Treatments may also affect the gemstone’s longevity, since emerald is brittle to begin with, and those with fillings may be less durable. So any treatments that a gemstone has undergone must be fully disclosed at the point of sale.

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