A 39-year-old jeweler in Great Falls has been accused of switching out his customer's diamonds with smaller, lower quality stones, police say.

Robert Mikail, of Loudoun County, was arrested on July 8 and charged with grand larceny with intent to re-sell and other charges, Fairfax County police said.

Police have been investigating Mikail, who owns Vima Jewelry store on Seneca Road in Great Falls, since April 6, when they first received a larceny complaint against him.

A 23-year-old woman said she had taken her collection of jewels to Vima for appraisal and discovered that a necklace and pendant worth $1,000 were missing when she returned home, said Fairfax County police spokesperson Lucy Caldwell.

Two months later, police said, a 43-year-old Potomac woman reported that Mikail offered to clean her diamond engagement ring while she browsed the store.

Mikail took the ring to the back of the store and returned a short while later, police said. The woman noticed the ring appeared cloudy and damaged and took it to an appraiser who determined that it was glass, police said.

On July 6, an undercover police officer took a dozen pieces of jewelry to Vima and left them with Mikail to be appraised, Caldwell said.

After picking up the jewelry, the officer took them to an expert appraiser who determined that one of the diamonds had been removed and replaced with a smaller, lower quality stone, police said.

Police said the investigation is ongoing.  

Mikail was arraigned July 11. His preliminary hearing has been scheduled for Aug. 3.