Unlike many modern cat breeds, the Russian Blue is a 'natural' breed which is believed to originate in Russia although the only evidence of this is anecdotal. They are found in many countries, and the majority of their modern breeding program has been carried out in the USA.
Although they have been used on a limited basis to create other breeds (such as the Havana Brown) or add type to a breed in creation (the Nebelung), Russian Blues themselves are shorthaired, blue cats.
Russian Blues should not be confused with 'British Blues' (which are not a distinct breed but rather a British Shorthair cat with a blue coat), nor the Chartreux or Korat which are two other naturally occurring breeds of blue cats.