BARCELONA, Spain — A suspected gang of diamond thieves who posed as potential buyers to steal a precious purple-hued diamond worth millions in Barcelona has been busted by French and Spanish police, officials say.

Police in Spain's northeast Catalonia region said Wednesday that eight suspected members of the criminal ring were arrested in Bondy, France, near Paris.

The police investigation started in Barcelona after the Jan. 2020 robbery of the rare diamond, estimated to be worth up to 15 million euros ($18 million) according to Catalan police. The investigation later linked the suspects with the theft of another diamond worth 4.5 million euros ($5.4 million) in Cannes, France, in August 2020.

Police said the thieves pretended to be interested in the purchase of the gemstones, only to switch the diamond case for a similar one after distracting the seller.