The levels are the levels of copy restriction. (however, they are quite useless because the key moulding technique can be applied, but I'm not sure if they have protection against it)
There are: (level descriptions taken from TOOOL)
Diamond Level: Additional keys are only available directly from Abloy. Full details of registration are required and will be checked thourghly
Ruby Level: Only the Abloy Protec center that issued the key origionally can make duplicates
Emerald Level: Very similar to ruby level.
Sapphire Level: Lowest and most common. A card must be presented to dealer to make duplicates.