In 1982, the old 400 was reintroduced under the name of Souverän (sovereign) M400, which was the beginning of the renaissance of the classic style fountain pen. M400 was the great success (Pelikan Schreibgeräte), which led to the introduction of Souverän M600 in 1985. M600 was a higher-end model of M400 and was the flagship when it was introduced. However, the only difference between M400 and the early M600 was the nib specification and decorative rings.

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• Dimension: Although a higher line of M400, M600 was the same size as M400. In 1997, M600 was enlarged in size, making it between M800 and M400.

• Nib unit: Unlike other models, M600 had its nib specifications changed several times. Initially, M600 had a monochrome 18 carat gold nib⁽¹⁾. The feed and collar were the same as M400, and the nib unit was screw-in fit from the start. In 1988, the nib was "downgraded" to a bicolor rhodium-plated 14 carat gold nib (Pelikan-collectibles)⁽²⁾. In 1990, the nib was "upgraded" to a bicolor rhodium-plated 18 carat gold nib (Pelikan-collectibles)⁽³⁾. In 1997, the body was enlarged in size, however, the nib was again "downgraded" to a bicolor rhodium-plated 14 carat gold nib (Pelikan-collectibles). In 2003, there is only one chick left in the logo on the nib.

• Cap: Basically, the cap was same as M400. The only difference was the cap rings: M600 had two (one thick and one thin) and M400 had one. The cap top Pelikan logo before 1997 had two chicks and was engraved. After 1997, the logo was embedded. In 2003, there is only one chick left in the logo.

• Body: Basically, the section and barrel were same as M400. The only difference was that M600 had a metal ring on the section.

• Filling system: Basically, the filling system was the same as M400. The filling system was friction fit to the barrel. The only difference was that M600 had a metal ring on the turning knob. After the size was increased in 1997, the turning knob had two rings.

 

When M800 was introduced in 1987, M600 relinquished its flagship position to M800. Since then, M600 has undergone nib specification changes three times and size change once. This was probably the result of Pelikan's attempt to distinguish M600 from M400 and M800, as well as to achieve consistency in price and grade. When introduced in 1985, M600 was the same size as M400, looked similar. Since M600 was enlarged in 1997, M600 began to claim its own position between M400 and M800. The model became the basis for many limited and special edition fountain pens, including the "City" series.

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Note;⁽¹⁾When M600 was introduced in Japan in 1986, M600 had a bicolor rhodium-plated 14 carat gold nib. The monochrome 18 carat gold nib became available in 1988. The 18 carat gold nib was often described as "soft" rather than "flexible" in Japan (万年筆評価の部屋). 

⁽²⁾This downgrade seems to have been made in response to the introduction of the higher-end M800 with a bicolor rhodium-plated 14 carat gold nib in 1987.

⁽³⁾This upgrade seems to have been made in response to the introduction of a bicolor rhodium-plated 18 carat gold nib into M800 in 1990.