As I've mentioned elsewhere, I'm curating my father-in-law's multi-generational coin collection. It includes the 1967
Royal Canadian Mint Set with the $20 gold coin. The silver coins are toned in an unattractive way (IMO, obviously), but the gold coin is flawless and beautiful.
My question is this: what is the best way to preserve and maximize value? Does the collector value premium lie in keeping the coins as a set? Or is there a particular collector premium on the gold coin that would warrant grading/slabbing it apart from the rest, since it is uncirculated and spotless?
Thanks for any advice.