No, roosters aren't the only ones with shimmery feathers. Rhode Island Red hens and roosters both have pretty, black tailfeathers. Roosters normally have very curled tailfeathers, though.
And many other breeds have beautiful, shimmery black feathers. Black Australorps, for instance. This is my Matilda.
The rooster makes use of those shiny feathers and (generally) brighter colors during a predator attack when his whole purpose in life becomes drawing the attention of the predator off the hens and unto himself.