Two thieves switched off power supply at 5 a.m. before breaking through a window into the Green Vault museum in Dresden, eastern Germany, which in the past boasted that it was "as secure as Fort Knox", a Daily Mail Online report said.
They smashed open the cabinet in which the three jewellery ensembles were stored, officials said. These were commissioned by Saxony's former ruler Augustus the Strong in an 18th century show of power.
Museum experts said the items are "priceless" and can never be sold. German newspaper Bild was quoted that treasures of up to a billion euros may have been stolen, which will make it the biggest art heist in history.
The thieves were caught on CCTV cameras inside the museum and have so far eluded arrest.
There have been a series of other famous thefts, including the theft of Mona Lisa painting in Paris which is vauled at $700 million in today's price.
The masterpiece by Leonardo da Vinci was stolen from the Louvre in Paris in 1911, but was recovered and returned in 1914.
Asked about the suggested value of a billion euros for the stolen jewellery, museum director Marion Ackermann told the media that the value could not be quantified.
"We're dealing with priceless artistic and cultural treasures. We cannot give a value because it is impossible to sell," he said.
Another museum director Dirk Syndram said the sets represented 'a kind of world heritage', totalling about 100 jewellery items.
State police were investigating how the thieves got inside and stole the jewellery. Reports from Germany said that the thieves were 'noticeably small' and able to fit through a tiny space in a window.
Police said they had neither identified the suspects not made any arrest.
( With inputs from IANS )