my 2 cents.
The original website of Tiffany uk is
http://uk.tiffany.com/ rather than
http://www.tiffanystore.co.uki) In their website, they do not even mention that they are the authorized agent for Tiffany.
ii) the price, i do not think it is genuine. (Nowadays they can even provide you with the so-call CERTIFICATE if you question them for authenticity).
iii) Tifanny & Co. website has its own taste and design. By compare those website provided by you. You can tell that ORIGINAL TIFFANY definitely do not fancy these designs..

iv) TIFFANY & Co. do listed and provide links to all others countries website and you can notice the uniformity of its design.
If you are really concern abt its authenticity, always buy from the original Tiffany.
Buying online through other's website gives no different in buying from Alibaba.
You may email their customer service in their website :
http://international.tiffany.com/Customer/...ailCustSvr.aspx (A representative will respond to your query within 48 hours.)
Well, cause this is the first time I'm buying something like this online so I'm not sure about the authenticity. Yeah, the price was actually what makes me confused. Thanks alot for the advice and also that official Tiffany & Co. website you gave me.