authentic V's genuine

i want to describe a designer brand clothing item.. its real designer
brand.. i have been told the word \"authentic\" is the best word to use to
mean - real, i have also been told the word \"genuine\" is not the best word
to decribe this. Do you think the word \"authentic\" is best for what i am
trying to do? thanks so much for your help, i eagerly await your reply.
cici

Either of those will get your point across.

As a legal matter it is not going to greatly affect you--assuming it is true of course.

[Don't sell fakes that you have not authenticated; people do get into trouble that way.]