"It was executed like a military operation," said Phelps. "They got around two major burglary alarms."
A total dollar amount of items stolen has not been determined.
"All I know is it's big," said Phelps.
What has been determined, however, is the damage to his store and Phelps estimates the thieves did between $15,000 to $20,000 in damage to some 15 jewelry cases.
In his 53 years in the jewelry business Phelps has owned 25 stores, including several in St. Johnsbury. Burglaries to his stores have occurred every few years.
"This is the 15th time I've been hit in 50 years," he said.
But in his 47 years in Littleton, Phelps said this is the first time his Littleton store has been hit.
Dana Jewelry was closed Monday, but reopened Tuesday.
Several Littleton police officers responded to the scene Sunday afternoon when the burglary was reported.
"I commend the Littleton Police Department," said Phelps.
Anyone with information on the burglary is encouraged to call the Grafton County Dispatch Center at 444-2422 or email firstname.lastname@example.org.