Well, it's not a real diamond. I took it two two jewelers and both said the same thing. They put some little device with a probe to the "stone", and it indicated it wasn't a diamond.
At the first store, I told the young lady behind the counter to just toss it in the wastebasket, which she did. As I walked out, I saw her from the corner of my eye take the stone (or whatever it is) out of the wastebasket and over to a work area. I gave it a couple of minutes, then went back in the store. Another woman was at the counter and I told her I had an idea for a practical joke to play on my wife, and would like the fake diamond from the trash. She rummaged around and couldn't find it, then said, "oh, Tammy has it over there", pointing to a table with a microscope and other gear.
I couldn't figure out why she'd be doing that, but it made me suspicious, so I took it to a second store just to be certain. It still didn't change into a diamond in that time.
I left it with the cute young lady in the office at the gym just in case someone is looking for it. Besides, it gives me another excuse to talk to her. (Actually, I look for excuses for her to finish the conversation and walk away. I just love watching her walk away
).