I know you asked 5 years ago but... The higher a magnet's coercivity, the more likely it will retain its magnetic characteristic even when stuck in a magnetic field of opposite polarity. Some magnetic materials, such as ceramic, have low coercivities, so they can have their magnetic qualities removed more easily. With stronger magnets, opposite magnets are sometimes applied to decrease their magnetic power so they're not too strong to be used. I just wanted to type all that out cuz it'd be funny.
