I always hold on to one if I have a question ... until I know for sure.
If there is only a few white hairs at the tip ... it's a tossup.
If the whole tip is white ... it's probably a mosaic.
Only time will tell.
Jo Ann
PS. When you have a standard that came from a white mosaic and a standard ... always remember to mark it as a standard/ possible white mosaic carrier.
There is a big difference between a pure standard and a standard that comes from a standard and a mutation, or a standard that came from two mutations.
When breeding, you want to use a good blocky pure standard to help keep the line strong.
I do not like to breed mutations to mutations for more than one or two generations. Just my personal practice.