Emerald is the green to greenish blue variety of beryl, a mineral species that also includes aquamarine as well as beryls in other colours.
Gem experts differ on the degree of green that makes one stone an emerald and another stone a less-expensive green beryl. Most gemologists, gemological laboratories, and coloured stone dealers call a stone green beryl when its colour is “too light” for it to be classified as emerald.
There are other green gems, like tourmaline and peridot, but emerald is the one that’s always associated with the lushest landscapes and the richest greens. Ireland is the Emerald Isle. Seattle, in the US state of Washington, is the Emerald City. Thailand’s most sacred religious icon is called the Emerald Buddha, even though it’s carved from green jadeite.
The birthstone for May, emerald is steeped in superstition and lore. It is the symbol of immortality and the symbolization of faith - it is also said to be beneficial to the eyes. It’s also the gemstone for twentieth and thirty-fifth wedding anniversaries.
The most desirable emerald colours are bluish green to pure green, with vivid colour saturation. The most-prized emeralds are highly transparent. Their colour is evenly distributed, with no eye-visible colour zoning. If the hue is too yellowish or too bluish, the stone is not emerald, but a different variety of beryl, and its value drops accordingly.
In Emerald expect to see inclusions that dealers like to call an internal “jardin,” or garden.
Due to the crystal shape emeralds are commonly cut as rectangular step cuts called emerald cuts.
Because its density is lower, a one-carat emerald will appear larger in size than a one-carat diamond.