What we want in a permanent magnet is a high remanence (measured
in gauss) and a high coercive force (measured in oersteds)
This is the site
http://www.netroglycerine.com/scitoys/scitoys/magnets/magnets.html#plastic
Another
measurement used to describe permanent magnets is the strength of
the
external field when the material is saturated multiplied by the
number of
lines of flux in the material at saturation. This number is the
energy
product, or the peak energy density, and is measured in gauss
oersteds