It means I think it is sterling silver. It has the 925 hallmark. As far as the karats, Its is a larger stone. I'm not big on rings so I looked it up and it is well above an 8.
I'm pretty sure its real. I have worn it often and it has never chipped or faded. my camera sucks so its hard to capture the glow. I work in a bakery ad wah dishes constantly. If it ere costume it would show wear. I have worn it over a year off and on and it shows no sign of wear.