In case someone,who's not that knowledgeable about locks stumbles on this thread this late from it's opening, here's my advice:
A. Ask one, or or if you are serious about it, more professional locksmiths.
B. It is a good (but basic) guideline to check the official certifications.
But if you are serious about it be prepared to spend some money on it. Good locks rarely come cheap.
But first of all let me remind you to think through what is exactly what you need in terms of security.
How secure do you actually need the lock to be (keeping in mind that the weakest link in a dorr could be the hinges and the door itself!)
A protection against illegal key copies?
Look for managed protections: (the factory only make keys for authorised individuals with required proof of entitlement, such as a security card.
Or for legal protections: Which means the keys are patented (Check out when the patent expires!)
Or for technology protection: (basically how hard it is to actually make a copy of the keys.)
The best is to go for all of them!
In case you are more worried about picking (for example in a closed space like a lab or so where foot traffic is heavy, you should look for a more manipulation (pick,bump..) resistant lock since this is the least noisy way to open a lock.
However if you would like to use the lock where rarely anyone walks by, it is safe to assume that any burglar will try more aggressive entry methods like drilling. In that case look for according protection.
So about the certifications:
EU Norm EN 1303 is one of them (for some details on the actual values and their meaning go to: http://security.ingersollrand.com/bumpa ... ained.aspx
Burglary resistance: DIN18252 ( a fairly detailed overview on page 2: http://www.schliess-anlagen.de/files/din1303.pdf
The Uk has it's own certification system: BSI Kitemark.
Germany has the VdS: (English language pdf:) http://vds.de/fileadmin/vds_publikation ... en_web.pdf
And a rather detailed guide to security certifications (!in german) from VdS : http://vds.de/fileadmin/vds_publikation ... 86_web.pdf
So if anyone who is looking for a generally good lock, should pay attention to the certification it comes with. All the testing institutions are meticulous and can be trusted to highlight the higher safety locks. Although keep in mind ,that they each test for specific things, so no certification means the world.
Hope I could help.