But, he was caught in just the nick of time by the stall owner who spotted him and alerted the police who arrested him.
The 32-year-old visitor, Chow Wan, asked the stall owner for a close inspection of the diamond and the stall owner obliged.
"He took out the diamond from the display case and appeared to be appraising it, when he suddenly put it in his mouth," a police officer at the scene of the crime said.
Chow was later rushed to hospital by the police to be administered laxative to flush out the expensive diamond.
