Wow. I knew ceramics typically will give lower inductance readings than alnicos.
Had no idea they could actually make a pickup read lower than its coils with no magnet.
quick readup:
magnetizing the steel (poles etc) alters its permeability (which influences the inductance), so the inductance might indeed be different with the ceramic than without a magnet at all
Sorry for the misinformation ...
When you look at strat pickups specs the bridge usually has a higher Henry number and many US strat pickup added screws between alnico slugs under the bridge coil to give the pickup more balls. I though adding iron did increase inductance. Also what we call ceramic magnets are actually ferrite, compressed iron oxide, which I assumed would have alot more iron than an aluminum alloy (alnico). Oh well it's the sound that matters.