My 316 brush has FRANCE imprinted on it. This came from the Pret-a-Porter collection so I know it's real. On one hand, if you bought it from ebay, there's a great probability that it might be fake, especially if it has a strong varnish/gas smell. Look at the handle if it is black with speckles and if it feels light. Most likely, this is fake. Also, if you see any corrosion or brick-red tint from the inside of the metal casing, this brush is fake.
To be really sure, try and compare the handle with a brush bought from MAC. You will see the difference in color, imprint, and weight. HTH a bit!