The thieves looted goods worth more than 113 million euros ($123m) from the Green Vault in Dresden in 2019.
The convicted men, who appeared relieved on Tuesday by the relatively light sentences, are members of the “Remmo clan”, an extended family mostly based in Berlin and known for a web of ties to organised crime.
The pieces stolen from the break-in at the Gruenes Gewoelbe (Green Vault) museum in Dresden in 2019 contained more than 4,300 diamonds with an estimated value of more than 113 million euros ($123 million).
They included a breast star of the Polish Order of the White Eagle and an ornate diamond headdress. However, police have said most of the stolen jewels have been recovered.
Six German men, all in their 20s, had been charged with aggravated gang theft and serious arson.
Five members of the same family were handed sentences of between four years and four months and six years and two months. A sixth family member was acquitted.
The plea deal came in for criticism, however, with the president of the Berlin prosecutors’ association, Ralph Knispel, noting that the defendants had not been required to reveal their accomplices.
“The question is what message that sends” to other criminals, Knispel told public broadcaster RBB.
Prosecutors said the men had sawn through part of a window grating in advance and re-attached it to get into the building as quickly as possible during the heist.
The stolen Dresden collection was assembled in the 18th century by Augustus the Strong, elector of Saxony and later king of Poland, who commissioned ever more brilliant jewellery as part of his rivalry with France’s King Louis XIV.
The treasures survived Allied bombing raids in World War II, only to be carted off as war booty by the Soviet Union. They were returned to Dresden, the historic capital of the state of Saxony, in 1958.