The man, thought to be in his 50s or 60s, arrived at and left the Chaumet boutique on a stand-up scooter on Tuesday afternoon.
He drew a weapon and threatened to set off a bomb he said had been planted in the store, police say.
The outlet is in an affluent area of the city near the Champs-Elysées.
CCTV captured images of the man entering the shop wearing a light-grey suit and a facemask.
Police say he forced employees to hand over the jewelry and stones and keys to the shop before locking the staff in as he left. No violence was used.
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