Is there a difference in electrical conductivity between Ag 999 and Ag 9999?

In fact, the target value for 9999 silver—at approximately 62 MS/m—is slightly higher than that for 999 silver, which is 60.5 MS/m. Of course, in practical measurements, the values may deviate slightly from the target value due to variations in temperature, minting, and packaging. The conductivity values of coins with a fineness of 9999 can therefore fall within the higher range and sometimes also within the lower range. The conductivity value of silver coins containing “only” 999 parts silver out of 1,000 occasionally falls within the lower range or even the adjacent lower range.