Emerald

Emerald is a Greek name “smaragdos” which means green stone.

It tends to have numerous inclusions and surface breaking fissures.Unlike diamond, where the loupe standard i.e. 10X magnification is used to grade clarity, emerald is graded by eye. Thus, if an emerald has no visible inclusion to the eye it is considered flawless. Stones that lack surface breaking fissures are extremely rare and therefore almost all emeralds are treated, "oiled", to enhance the apparent clarity. Eye-clean stones of a vivid primary green hue with no more than 15% of any secondary hue or combination (either blue or yellow) of a medium-dark tone command the highest prices. This relative crystal non-uniformity makes emeralds more likely than other gemstones to be cut into cabochons, rather than faceted shapes.

It's common knowledge in the trade that most emeralds are treated; some are filled with oils, such as cedar wood. Others are filled with polymer resins to hide surface-reaching breaks and improve transparency. As with most treatments there's nothing wrong with this as long as the buyer knows that the stone they are buying is treated.

The birthstone for May, emerald is steeped in superstition and lore. It is the symbol for immortality and the symbolization of faith.