Rothe held many positions, including more than one "Minister" title. His first name gets spelled Carl or Karl, depending on the linked info.
http://webcache.googleusercontent.c...r+rothe+carl+zeiss?&cd=11&hl=en&ct=clnk&gl=us
"The Carl Zeiss donation was created by the physicist and mathematician Ernst Abbe. The charter of foundation dates of 19. May 1889. ... The donation administration was with Weimar ministries for education and cultural. From there came the donation commissioner, who led the supervision across the enterprises. The executive committees of the enterprises were appointed by the donation administration. The first donation commissioner was until 1896 Carl Rothe".
Rothe (1848-1921) retired/resigned in 1918 from his Minister of State position and died in 1921, which would fit the time for the above mentioned dates:
http://geociti.es/CapitolHill/Rotunda/2209/Saxe_Weimar.html
GRAND DUCHY OF SACHSEN / SACHSEN - WEIMAR - EISENACH ~
Staatsminister 1 Jun 1899 - 8 Nov 1918 Karl Friedrich Otto Rothe, resigned at the outbreak of the November Revolution.
http://en.wikipedia.org/wiki/List_of_people_related_to_Mainz
Honorary Citizen ~ 1898: Dr.jur. Carl Rothe, administrative director of the province Rheinhessen, Ministry of Internal Affairs within the Grand Duchy of Hesse.
http://translate.google.com/transla...-1920&hl=en&rls=com.microsoft:en-US&prmd=ivns
Honorary Citizen of Jena: Karl Rothe (born July 10, 1848 in Großrudestedt; † 28 April 1921 in Eisenach), Privy Council, Excellency, Minister of State, awarded on 1 August 1908; hat sich um die Stadt und Universität die größten Verdienste erworben. August 1908, the city has the greatest merit and University purchased for.
It may just be a medal honoring his years of service to the Zeiss Foundation, which is why there was only one link to a sale of it (the ebay one above).
Here's a link to The Zeiss Historica Society (hopefully they can help or steer you in the right direction):
http://www.zeisshistorica.org/