This is from the book The Guitar Pickups Handbook by Dave Hunter
Alnico magnets
II weaker magnet softer and sweeter
III soft but richer and slightly bolder
IV noticeably punchier more definition in the highs
V bolder, cleaner and more aggressive still
Of course the shapes of the magnets also effects the sound.
Guitars: Epiphone Les Paul Ultra; pretty red Squier Acoustic;
Amps: Vox VT30;
Pedals: Dunlop Fuzz Face; Dunlop Crybaby Wah
My kids have: Squier Affinity Stratocaster MII; Fender G-DEC; Squire Acoustic; Jay Turser Strat-copy, Roland Cube amp
"I am a sworn enemy of the saccharine, and a believer in grace over karma." Bono 2001