There have been 10 smash-and-grab robberies at jewelry stores in New Jersey since January.

So far, no arrests have been made in those daytime heists.

One of those robberies took place this week at the Bloomingdales in Hackensack. Others have taken place in Perth Amboy, Woodbridge, Bogota, Wayne, Jersey City and Edison.

In the majority of the incidents, there have been multiple masked thieves breaking through windows and doors with a sledgehammer.

They carry large bags to clear out jewelry cases and have a waiting stolen car parked outside to get away.

The nonprofit organization, Jewelry Security Alliance, which is assisting in the police investigations has suggested New Jersey stores enlist armed guards to keep from being victimized. While surveillance cameras are also suggested as help, they haven't deterred any of these incidents from taking place.

The organization's executive vice president Scott Guginsky says the favorable price of gold at over 4,000 per ounce is one reason these types of robberies keep happening.

“As the value of precious metals increase, we’ve seen the increase in violence and targeting of these jewelry stores," said Guginsky.

When asked if he thought these 10 cases were related he said, “I don’t believe there’s one group responsible for all 10. We have a couple of different groups that are responsible."

Guginsky says often after jewelry is stolen, it is sold back into the jewelry market, melted down or sent overseas.