Haggle with the woman.

Haggling

Why not make an offer and haggle it?

"I'll give you $50 for it." She frowns at your offer.
"I'm sorry, but it's priceless. Please hand it back to me."
"Sixty dollars."
"Please--"
"Eighty dollars."
"--I am not--"
"One-hundred dollars."
"--going to accept--"
"Five-thousand dollars."
"--any less than five-thousand dollars! Sold! Would you like a bag?!?!"

The next few minutes go by as a blur. You find yourself standing outside holding a "five-thousand dollar"-necklace and a twenty-five cent-pack of gum. In retrospect you actually meant to say five-hundred, not five-thousand, but it is too late now.

You turn back to glance inside the inoccuous little shop that just stole your tuition money. The lights are off, the old lady is nowhere to be seen and the sign on the door says, "closed." Amazing.

Diane is probably still upset, so you might save this gift for later, but you can also see the wisdom of taking care of this now, before it potentially gets worse.