I think I understand your confusion, you're mixing up the terms lustre and brilliance.
Mint bloom/Lustre is the natural reflectivity of a coin (usually cartwheel or mirror)
Brilliance is the natural colour of a coin (i.e. red copper, white silver, etc)
Mint bloom/Lustre is the natural reflectivity of a coin (usually cartwheel or mirror)
Brilliance is the natural colour of a coin (i.e. red copper, white silver, etc)


















