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TREATED EMERALDS

Fracture filling The most common treatment associated with emeralds is fracture filling. As in diamonds, a surface reaching fracture is filled with a material that disguises the fracture. Emeralds are routinely filled, and we consider any emerald that we deal with to be fracture-filled unless we can prove otherwise.

The filling material varies widely from natural and chemically manufactured oils to polymer resins. Though there is debate within the emerald trade as to which substances are better suited, more durable, or more "natural," it is nearly impossible to determine what the actual substance is without using Raman Microspectrometry. However, it is possible to spot the presence of a filler within an emerald's fractures using a microscope.

First, observe the emerald in reflected light in order to locate surface reaching fractures. Then, using darkfield illumination, look carefully for the fracture within the stone, while moving the stone in several directions. Filler in a fracture may show an unusual colour flash as the stone is moved; the colour is similar to that seen in fracture filled diamonds. The most common colour of this flash that we have observed is yellow, although others are possible. Remember, though, that the colour of the emerald may disguise the color flash or make it more difficult to detect.

Fillers may also have gas bubbles trapped within them or show a flow structure. Gas bubbles and flow structures are more common in wide fractures and depend on the filling material.

Over time, many fillers deteriorate and turn yellow or partially leak out of the fractures. Still others are whitish in colour and fairly easy to see using a microscope. In lower end stones, we have noticed that the fillers are sometimes dyed green to improve the overall appearance of the stone. On higher end stones, dealers tell us that they try to remove the fillers with acetone or other similar chemicals. This can result in a finger-like or dendritic mass of filler left in a fracture (figure 7).

All of these characteristics are fairly easy to spot. We recommend sending high-end stones that appear free of filling material to a laboratory with the ability to do advanced testing and issue a report.

GOLD	SILVER	STONES	HALLMARKING	HISTORY OF GOLD	HISTORY OF SILVER

Disclaimer
Opinions and interpretation of law expressed here are my own. If you stand to lose as a result of any decision based on information here you should seek appropriate legal advice. I give this information freely, and cannot accept any responsibilities for losses you may incur. Nor can I accept responsibility in the unlikely event of inaccurate or misleading information. You alone are responsible for your actions.
Also while much of the information is relevant throughout the EU, I have written with particular regard for accepted practices in the UK.

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