04-18-2003, 10:58 PM
..."Superior" shields do not get enhanced blocking, as far as I can recall. That being said, no, you will not lose any enhanced properties by inserting gems into the socketed shield. It retains the exact base item, rather than "rerolling" it. As such, while it may be labeled "Gemmed Tower Shield", it will in fact retain its enhanced properties from the "Superior" mod, i.e. increased Defense Rating or Durability.
Roland *The Gunslinger*