Ritz-Carlton's use of cobalt-blue glasses in its hotel dining rooms can be traced back to Boston in the 1920s, for example, where window glass that had been imported from Europe and turned blue in the New England air was a symbol of wealth.

ECONOMIST: Corporate history

Each morning, fleets of cobalt blue boats still head out from port, scattering across a vast Atlantic horizon - but now the daily haul is sea bass, not sugar.

BBC: Morocco��s best for coastal retreats: Essaouira