The gemstone for May is the emerald. It is such a lovely gemstone, with a surprising range of green tones available. The emerald in the Georgian signet ring at the top of this post is a green with a very faint touch of blue, while the emerald in the antique pendant/brooch is a light clear green. The other two photos below show emeralds of a darker green hue. The emerald has been used for jewellery for over 4000 years due to its striking colour.
The emerald is a tricky stone because, although it is a hard stone, it can be quite brittle. This feature led to way the emerald is cut, resulting in the emerald cut which has a flat table and stepped sides, thus reducing the possibility of chipping. It is not the only cut used though, as seen in the following photos.
Emeralds can also have a lot of natural inclusions and fractures, and have been traditionally heated and oiled to fill the fractures. Inclusions are good though as you know that the stone is natural and that it is not a synthetic stone.
There are a number of other transparent green gemstones, for example, tourmaline, demantoid garnet, peridot, tsavorite garnet and chrome diopside, but the emerald remains the most desired one.