Ridges in the nails are usually heavy metals being built into the nails.
When you've got heavy metals running in the blood or in the system anywhere, they have a tendency to magnetize other metals. So, when it builds into the nails, it's too large of a structure, too large of a unit, so it creates these ridges, the body built it out
It's one way the body gets rid of it, builds it into the nails to get it out. It also does it into the hair.