Is the setting costume jewelry or gold or silver? If the setting is junk, the stone probably is too. Also, real stones almost always have inclusions like cracks, wispy stuff, black spots, etc. The color reminds me of Tourmaline. I guess taking it to a jeweler would be the easiest way to find out. Nice find, I like it.
Could be an emerald. Any inclusions (dark areas) in stone? If so likely to be real. If not, and colour too uniform throughout, probably a heat-treated stone. Ask a jeweller.
In that light/photo , the stone does look more like tourmaline - Emerald has a green that is unique to emerald - the other comment about
the metal quality is correct as well ! keep us posted .
Don't think its real... Placed it over an open fire the thing did not smoke or melt but did turn red as a piece of iron. I also noticed that it made whatever cracks in it more visible. I'm thinking its glass/costume jewelry. As for the setting, i noticed it had a black film of sorts (possible plastic). I also tried the magnet test and the thing didn't not catch. Might be aluminum. Oh well...! dde1e