INTERPOL has issued a worldwide alert for the "priceless royal jewels" stolen from the Louvre museum in Paris on Sunday, a heist that French authorities have now valued at $157 million.
The international criminal police organisation distributed a "special edition poster" among its members picturing the exquisite relics from France's imperial past, amid mixed hopes they would ever be recovered.
"We can confirm that at the request of French authorities, the items stolen from the Louvre have been added to INTERPOL's Stolen Works of Art database and circulated to our membership," its press office told the ABC.
The eight missing "priceless royal jewels from the first and second French empires" include crowns worn by the country's last queen, Marie-Amelie, and its last empress, Eugenie.
The jewellery has been listed on a database of more than 57,000 stolen artworks from around the world.
Experts see the listing as a key barrier to the loot being sold in the immediate aftermath of the robbery.
French public prosecutor Laure Beccuau reportedly told France's RTL radio that the missing jewels, according to a curator at the Louvre, were valued at 88 million euros ($157 million).
Ms Beccuau said she flagged the price tag to persuade the thieves against "the very bad idea of melting down these jewels" in a bid to cash in without capture.
"We can maybe hope that [the perpetrators] think about it and won't destroy these jewels for no reason," she said.
Ms Beccuau said there were four main suspects who may have had accomplices.
INTERPOL said the robbery was "brazen", with thieves using a "mechanical ladder mounted on a vehicle" in public view to enter the Louvre's Gallery of Apollo.
"They cut through the display cases and fled with the culturally significant items, which date back to France's 19th-century royalty and are encrusted with thousands of diamonds and other precious gemstones," INTERPOL said.
"A crown once belonging to Empress Eugenie of France was recovered from the scene, seemingly dropped by the intruders."
The thieves reportedly made off on scooters after museum staff foiled their attempts to set fire to their vehicle outside.
French President Emmanuel Macron has vowed authorities "will recover the works" but art theft commentators fear they will never be seen again.
