BERLIN (NYT NEWS SERVICE ).- The Royal Palace museum in Dresden, Germany, reopened to the public Wednesday, except for the rooms known as the Green Vault, where police continued to hunt for evidence to help them track down the thieves who broke in two days earlier, making off with 11 rare Baroque jewels.

Police said evidence indicated that four thieves had carried out the robbery early Monday, spraying a fire extinguisher in their wake to erase their tracks. The thieves broke an iron gate and a window to enter a room in the Green Vault on the ground floor of the museum.

Among the treasures in the Green Vault — founded by August the Strong, prince-elector of Saxony and king of Poland — were several sets of royal jewels. The thieves used an ax to break the security glass and steal three of them — the “Diamond Rose,” “Diamond” and “Queens’ Jewelry” sets — taking a total of 11 entire pieces, parts of two other pieces and several buttons, Dirk Syndram, director of the Green Vault, said Wednesday.

“These three sets included diamonds in various cuts that date largely from the time of August the Strong and August III,” Syndram said in a statement. “They were set between 1782 and 1789.”

Among the items stolen were a sword with a diamond-encrusted handle, several shoe buckles and buttons made of diamonds, as well as brooches, a hair clip shaped like the sun and parts of a diamond necklace belonging to Queen Amalie Auguste from 1824.

Police have appealed to the public for tips but have so far found no trace of the thieves.

One piece from the “Diamond” set, a hat clip with a flawless 41-carat gem known as the Dresden Green Diamond, is currently on loan to the Metropolitan Museum of Art in New York for an exhibition. Even when in Dresden, the diamond is displayed separately from the rest of the set on another floor of the museum.

The theft has raised concerns about security at museums around Germany.

Marion Ackermann, director of the Dresden State Art Collection, a consortium of museums that holds the treasures of the former royal house of Saxony, has repeatedly defended the collection’s security.

But Germany’s culture minister and the German Museum Association said they would discuss how to better protect the treasures in the country’s museums, while still keeping them accessible to the public.

Eckart Köhne, the association’s president, said in a statement, “The break-in at the Green Vault gives us a reason to re-examine whether the threat level has changed in recent years.”

“For this, the museums need assistance from their sponsors, as well as police and security specialists,” he added.

A surveillance video released by police shows two figures, one carrying a flashlight, approaching a display case enclosed in glass. One then bends down, pulls an ax from a bag and repeatedly slams it into a panel of glass, which fragments and gives way.

“The case looks like a battlefield,” Syndram said.

The stolen jewels were not insured, and Ackermann and her team would not give a figure for their value, insisting that their worth lies in their historical and cultural significance as part of an intact set of royal jewels.

Because they are unique, they could not be sold on the open market, she said.

That has led to fears that the pieces will be broken down, the gems re-cut and the gold melted to render them sellable.

“Of course, if the pieces remained intact, the entire world is looking for them and they are not going to find much of a market,” said Chris Marinello, an expert with Art Recovery International, which specializes in finding and recovering stolen art.

“Every hour that goes by increases the likelihood that these are going to be broken up and destroyed,” he said, adding that he hoped the authorities would promise a reward for the return of the intact pieces.

Art historians and museum directors across the globe have joined in the outrage at the loss from a collection that was hidden to survive the Allied bombing of Dresden at the end of World War II. The treasures were later taken by the Soviet Union but were returned to the former East Germany in the 1950s.

“They bear with them that history,” said Shira Brisman, an assistant professor in art history at the University of Pennsylvania who specializes in art produced in German-speaking regions from the period.

The objects in the Green Vault collection are signs of power, Brisman said, artworks that could show off Saxony’s mining wealth, including tin, silver, copper and precious stone, and the skills of its artisans.

“On the one hand, they reflect wealth,” she said. “On the other hand, they reflect alliances.”

After its return to East Germany, the collection languished in relative obscurity behind the Iron Curtain for decades, despite their status as the biggest surviving princely art collection in Europe.

The Green Vault was partly destroyed during World War II but was rebuilt after German reunification and opened in 2006.

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