The Diamant was an express train operated by the Deutsche Bundesbahn (DB), using different routes over the years.
[4] In May 1966, only one year into the train's TEE era, its western terminus was changed from Antwerp to Brussels (South/Midi), disconnecting the "Diamond" (Diamant) from the place that had been the inspiration for its name.
[6][7] The Diamant was reintroduced on 27 May 1979, again as a TEE but no longer an international service, instead taking over the Munich – Hamburg section of the Blauer Enzian.
The third Diamant was a two-class DB Intercity service linking Hamburg with Stuttgart via Cologne, from 29 May 1988 until 1 Juni 1991.
Although normally a non-international service, the IC Diamant was extended to (and from) Innsbruck on Saturdays during some periods, including at least January through May 1991.