Close collar minting is a method of coin manufacture that is used almost exclusively today.
[1] This restraining collar prevented the expansion of the planchet sideways and outwards and thus made it possible to mint completely round coins for the first time.
A pearl circle often adjoins the edge bar on the inside.
Close collar minting is an invention of French medalist and engraver Jean-Pierre Droz (1746–1823).
In Germany, Prussia systematically promoted such coinage via the German Customs Union from the middle of the 19th century.