The problem is with the use of the word 'fine' instead of a dimension or reference to a standard.
I'm sure it was perfectly clear to the spec writer, within his or her little world.
To other people, 'fine' may mean 'just passes an egg rock', or it may mean 'just passes a blood cell', or anything in between.
You need to ask the supplier for a number, or at least a context.
Mike Halloran
Pembroke Pines, FL, USA