A green Beryl gemstone from Colombia.

The gem owes almost all of its colour to the artificial introduction of coloured oil and/or resin, an enhancement intended to imitate Emerald.

On close examination, the colour is clearly restricted to the many internal fractures within the gem.
This is most apparent when the stone is placed on a white background, with most of the gem appearing colourless.

Under the microscope (images 4 and 5) the enhancement is clear to see, with patches of paler and deeper green inhabiting the fractures. Some of these colour patches display a diagnostic "dendritic" pattern, a clear sign that the introduced dye has congealed.

A perfect reference specimen for those interested in gem treatments and enhancements.

weight:  5.71 carats
shape:   Emerald cut
dimensions:   11.65 x 9.18 x 7.30 mm
treatment:  Coloured oil/resin treated