An alarm technician at an Oceanside jewelry store was arrested on a grand larceny charge Wednesday after he stole an envelope filled with jewels worth more than $20,000, police said.

The incident occurred March 31 at Forever Diamonds Jewelry, 50 Atlantic Ave., Nassau County police said in a news release.

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While in the store's repair shop room, Fernando Robles, 50, of Orlando, Fla., took two envelopes containing jewelry valued at $20,700, without permission, police said.

Robles was charged with third-degree grand larceny, police said, and is scheduled to be arraigned Thursday at First District Court, Hempstead.