I Am Looking At Buying Some Tiffany And Co And Links Of London Jewelry, Are The Unoffical Sites Such As?

tiffanystore.co.uk and linksgift.co.uk selling offcial and genuine jewelry, the same as what you would get from the official sites. i am only asking this as the difference in prices is alot ! and i am looking to get my girlfriend some for her birthday this month, however i really want to make sure its the genuine stuff
please help
Thanks