Can anyone help me with this diamond ring dilemma?

I thought I would sell my mom's diamond engagement ring as she is passed away and I desperately need the money. I thought I could get at least $500 for it. She always told me how she and my dad went together to the jeweler and picked it out. Today I took it to a jeweler. He examined it and told me that it was not a real diamond at all and worth nothing. He said he would give me $60 for the band since it is 14ct. gold. I was astonished. My mom always said how dad paid quite a few hundred for it, even thought he was having a hard time financially. Do you think the jeweler I saw today was lying? Does this happen? I would greatly appreciate your opinions. Thank you.