One of the characteristic features of emeralds is that they naturally contain inclusions and microcracks. The reason is that there are no alluvial deposits of emeralds anywhere in the world and the process of uncovering them beneath the Earth entails exploding hard rocks, as well as making use of various mining tools and machines. Crushing the extracted ore, meanwhile, allows it to be broken into pieces and brought to the surface, where the valuable green specimens can be sorted out.
It is easy to imagine just what happens during an explosion – this method of mineral extraction invariably leads to the formation of microcracks in the precious rock. It is also worth noting that emerald scores 7.5-8 on the Mohs scale, which measures the hardness of a stone, third among the precious gems after diamond and corundum. The slight cracks that emerge as a consequence of the extraction process may not be conspicuous, but they can cause increased fragility. To eliminate microcracks – which, despite the name, are often far from small – a jeweller may resort to enhancements that involve treating the emerald with oil or resin. Oil is generally used for minor cracks and works to improve the stone’s transparency, with resin reserved for specimens that have significant splits and have suffered greater damage. The resin acts as a kind of glue to increase the strength of the stone.
All of the above means that emerald jewellery requires special care. Follow these simple rules to keep yours looking its best:
1. Regularly wipe the jewel with a microfibre cloth to ensure it is kept clean at all times.
2. Emeralds should never be cleaned with ultrasonic or steam, which will remove the oil filling the cracks and can even increase the size of existing cracks.
3. If you spot some dirt on an emerald and you can’t remove it with a simple wipe of a cloth, use a cotton swab soaked in warm water. As a last resort, the cotton swab can be replaced with a soft toothbrush.
4. Only re-set an emerald after it has been thoroughly checked by an expert to avoid the emergence of chips or new fissures.
5. Emeralds are better suited to earrings and pendants, which are less prone to shock and abrasion compared with rings and bracelets.
6. Additionally, avoid showering, washing dishes or playing sport in emeralds, or any activity that risks exposing them to additional damage.
Emerald specialist George Smith of the International Emeralds Exchange shares his perspective: “It is very important to treat your emerald with care in order to reduce the likelihood that it will need additional cleaning. I believe that, in some cases, emerald can be a gem for everyday wear – it really depends on the setting. If the stone is exposed, the chance that you will catch it on something and damage it is higher, but if the setting envelops the stone from all sides, protecting the corners, one can certainly wear it daily and not merely on special occasions.”
If we consider the topic of emerald fragility under a microscope, another important fact becomes obvious: the colour of the stone is central to the problem, or, to speak scientifically, the presence of chromium (Cr), which is what gives an emerald its famous green hue but also distorts the stone’s crystal lattice, making it more fragile. Other stones in the beryl family to which emeralds belong, such as aquamarines, heliodors and morganites, also contain iron (Fe) and manganese (Mn), which greatly reduce the distortion.
Each emerald deposit has its own unique chemical composition. The most popular are stones with certain sought-after optical properties, for which a larger chromium content is primarily responsible. Of course, not all emeralds are “lucky” enough to grow in conditions where Chromium is abundant. If you read my articles regularly, I am sure you can guess which region is famous for having the highest Chromium content – the Colombian emerald deposits in Muzo, Chivor and Peña Blancas, of course.
The stunning beauty of the emerald is inextricably tied to its fragility. Take care of your gem, always be mindful of its unique features and, in return, it will bring you great pleasure for many years to come.