I would use the authentication threat available at http://forum.purseblog.com/gucci/authenticate-gucci-read-rules-use-format-posts-1-a-689655.html
I have used this thread several times and they have saved me hours of worries. It may take a day or two to receive a response but it is worth it.
Also, Ebay has some good Ebay guides available that offers tips and suggestions about how not buy a fake "Gucci Horsebit" bag which can be accessed at http://reviews.ebay.com/Gucci-Horsebit-Hobos-Gucci-Handbags?ugid=10000000003842739
thank you so much!