Real or Fake?

I am working in my spare time (which is not much) at my grandparents house again, trying to get things ready for their final moving sale. I had some really wonderful help tonight from my Aunt's "J" & "G" but we are stumped on how to tell if jewelry is real or fake? I know that my grandma has some real jewelry but I also know she has some fake stuff also. The bad thing is, is that it is all mixed up together and I don't know what is what. And if you ask her, none of the jewelry is hers, she does not know where it came from. And as far as grandpa is concerned he doesn't really know much anymore either. He tried to tell me the other day that a jewelry box on top of the dresser was an antique. I believed him until I found the box it came in that had a price sticker on it from a store in our town that has only been there about 10 years. So I am now taking caution in things he says.

Anyway, back to the jewelry. I don't have time to take it to a jewelry store or the money to pay them to tell me what it is, so I am stumped on what to do. I am having the sale this Friday and Saturday and running out of time. Does anyone have any idea's?