Francly(sorry for the pun) a lot of the earlier coins are not graded because they are usually held by collectors in Europe. The earlier Helvetia coins are not collected as avidly in N. America as they are in Europe, and they tend to have a premium value to collectors that is in excess over melt value:
The later "Swiss Miss" coins especially the 1935 and 1940's coins are defined as bullion because they were not created for coinage like this one:
These earlier coins are usually numismatic, especially in high grade, and are not traded like bullion and largely not going to N. America to be graded. These two examples went to N. America to be loved and adored by their Master's Golden Lovelies Harem.
