BERLIN — Thieves broke into a museum in the eastern German city of Dresden early Monday and made off with three collections of jewelry from the royal house of Saxony, made of gold and precious stones, that authorities said were of immeasurable historical and cultural value.

The break-in took place in the Jewel Room, one of 10 rooms in the Royal Palace known as the Grünes Gewölbe, or Green Vault. The rooms hold a collection of 3,000 individual objects, gathered by August the Strong, an 18th-century ruler of the German state of Saxony, as well as of Poland and Lithuania.

At least two thieves broke the special security glass of a display case and made off with an unknown number of objects from three sets of royal jewels comprising more than 90 individual pieces — cuff links, buttons and brooches adorned with rubies, sapphires and diamonds — the Dresden police and museum authorities said.

“I don’t have to tell you how shocked we are by the brutality of this break-in,” Marion Ackermann, general director of the consortium of museums known as the Staatliche Kunstsammlungen, of which the Green Vault was a part, told reporters hours after the crime was discovered. “As you know, the historical and cultural value of this is immeasurable.”