Gotta love Google. Just typed in "American Express black card" and got this info:
AMERICAN EXPRESS INTRODUCES THE CENTURION CARD
Black Card Sets New Standard For Premium Service With Free Upgrades on British Airways Concorde® and Enrollment in Elite Airline Frequent-Flier Programs
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NEW YORK, October 14, 1999 -- American Express today announced the introduction of the CenturionTM Card. The Centurion Card will be offered by invitation only to selected Platinum Card members.
The black-colored Centurion Card offers customized personal service to help ease the busy and demanding lifestyles of cardmembers. It has been designed for individuals who travel frequently, entertain often and value single points of contact for service.
“We created the Centurion Card in response to customer research that identified a small but affluent group of cardmembers for whom individual attention and access to previously unavailable elite travel benefits was of great interest,” said James Bush, senior vice president of Consumer Marketing at American Express. “Many of our prospective cardmembers are already frequent travelers receiving elite benefits on one airline. The Centurion Card is the only product on the market that can grant them elite status on four airlines, and much more.”