Alright...you stop to eat. You have shopping bags and a diamond bag. You put them under the table while you eat. You pick up all the shopping bags but leave the diamond bag?

Must be he left it behind unless someone got under the table while he was eating and took it. The article says the bag was found empty.

Somehow you don't see that you left the diamond bag behind or you don't see someone crawling under your table? Yeah, right!