In 1912 Claude installed the first-ever neon advertising sign in a Parisian barbershop on the Boulevard Montmartre. A large rooftop sign for the Italian vermouth maker Cinzano soon followed, along with illumination for the entrance of the Paris Opéra. Ne or neon gas is used for advertising signs, as are other noble gases. ... The gas itself has no color until an electric charge is applied that alters the structure of the Ne molecules. Neon gas only produces a reddish orange color light, so other inert gases are used to make other colors.
