Sometime in late 80's or early 90's, Campagnolo introduced the "century" and "graphite" finishes to their product lines. Century was strictly for Record, and was a sort of smokey chrome. Graphite was available in the "lesser" component groups, and was a darker, opaque grey/black.
Graphite finish items show up relatively infrequently. Even less common are items in century finish, like these beauties that followed me home recently:
If you check out the Campagnolo catalogs, you won't see either finish pop up until the 1991 catalog. I have a hard time using catalogs as cannon in these situations - you'll also note that the last generation criss-cross style (often called the 5 pivot style) was available by then, and all delta's in the catalog sport black accordians and wheel guides.
Not so with my brakes. The Chorus cranks above have a '51' in a box for a date code, which I've been led to believe indicates 1989. Who knows when they really appeared? 1989? Possibly for the 1990 catalog year?