For tips how to get the best reads I suggest you read the following threads: List of sewwtspots Thread about the Nexus 5 with tips and tricks To be able to use the nfc ring unlock app you need to enter a verification code once. this code can be set via the nfc control app under the section registration (it will ask you for a password and that will be the verification code) sadly we have currently some problems with a bunch of rings and some people (like you) get the error message "not nfc ring". The teams is currently working on resolving the issue. I suggest you follow this thread since there will be the updates on this issue. I hope this helps you a bit further