In the 1939 classic film “The Wizard of
Oz,” Dorothy visits The Emerald City, so named because virtually the entirety
of the city is, in fact, emerald in color. As you may know, the film is not always
completely faithful to the book upon which it is based. In L. Frank Baum’s
original “The Wonderful Wizard of Oz” (1900), while the walls of The Emerald
City are green, the city itself is not. In the book, upon entry into the city,
everyone is required to wear green-tinted spectacles (explained as an
effort to protect the eyes of the residents from the "brightness and
glory" of the city). These spectacles have the effect of making everything
appear green even though the city is objectively no greener than any
other.
Dorothy
was shocked to learn the truth from the Wizard of Oz: “But isn’t everything
here green?” asked Dorothy. “No more than in any other city,” replied Oz; “but
when you wear green spectacles, why of course everything you see looks green to
you…[M]y people have worn green glasses on their eyes so
long that most of them think it really is an Emerald City…[i]
Given that the reason that the residents of the city believe it to be emerald is the filtering effect of their colored glasses, it follows that if instead of green tinted spectacles, they wore scarlet tinted spectacles, the residents would think they lived in The Scarlet City. If they wore turquoise tinted spectacles, they would believe that they lived in The Turquoise City. If the residents wore magenta tinted spectacles, they would think that they were residents of The Magenta City. And so on…