A platinum necklace set with 673 diamonds, once worn by former Egyptian Queen Nazli, was stolen from Vienna’s Museum of Applied Arts (MAK) on Thursday afternoon. Police said two men who had entered with tickets smashed the display case with hammers during an exhibition and left the museum with the necklace. Security cameras recorded images of the suspects, who remain sought by police.

The necklace contains diamonds weighing a combined 200 carats. Queen Nazli wore it at her daughter Fawzia’s wedding in 1939, according to exhibition records. The piece sold for US$4.3 million at a Sotheby’s auction in New York in 2015. It was included in a Van Cleef & Arpels jewellery exhibition that had been running at MAK since June.

Police searched central Vienna after the theft and used a dog to help find the suspects. Austria’s Krone newspaper reported that investigators suspect the theft may have been commissioned by a criminal network. Several people were in the exhibition room, but nobody was injured. A guided tour scheduled for Friday afternoon was cancelled and the exhibition was temporarily closed; it had been due to end on September 27.