A Sound Beach man was arrested yesterday for stealing diamond rings from sellers he met on the internet, Suffolk Police said.

Suffolk police said John Cumbow, 29, contacted sellers of diamond rings on the internet classified Web site, Craigslist.com, arranged meetings at jewelry stores to get appraisals and discuss a potential sale. In two cases, Mr. Cumbow was able to swap the real ring with a replica during the meeting and leave the scene before the owner noticed, police said. In the third case, Mr. Cumbow fled the scene with the ring, police said. Mr. Cumbow would sometimes use a stolen pickup truck as the getaway vehicle,  police said. Mr. Cumbow was also able to steal a diamond ring from jewelry stores in both Dix Hills and Sayville and, in both cases, police said, he was able to get possession of the rings while discussing a possible purchase with the store's staff.

Mr. Cumbow was charged with four counts of third-degree grand larceny and one count of fourth-degree Grand larceny in relation to the diamond ring thefts. He was additionally charged with three counts of seventh-degree criminal possession of a controlled substance, criminal possession of a hypodermic needle, resisting arrest and third-degree criminal possession of stolen property. Mr. Cumbow had two outstanding warrants at the time of his arrest, one for criminal possession of a hypodermic needle and another for seventh-degree criminal possession of a controlled substance, according to police.

Mr. Cumbow was also wanted for passing counterfeit $20 bills two years ago, and was charged with first-degree criminal possession of a forged instrument.

Mr. Cumbow's girlfriend, Amanda Carullo, 21, of Holtsville was also arrested yesterday in connection with two of the diamond ring thefts. She was charged with two counts of third-degree grand larceny.

Police are asking anyone who believes they may also have been victimized by Mr. Cumbow to contact the Sixth Squad at 631-854-8652.

Both were held overnight for arraignment at First District Court in Central Islip.