Alberta Diamond Exchange.
https://www.abdiamond.ca/
I had a great experience with these guys earlier this year.
You book an appointment. On the day of they buzz you into one room. You close the door behind you and it locks. Then they open a second door that lets you out of that first room and you're now in their reception area. You go into an office and they sort your items to determine quality of the gold/diamonds/whatever. They take the current spot price and make you an offer.
I found their offer to be very fair. They cut you a cheque right then and there and you're done.