How to tell silver nickel and nickel nickel apart?

Ok I'll take a break from sorting.  I found a 1942 nickel from the USA.  What's the best way to tell if it's a silver alloy nickel or the plan nickel nickel?  It doesn't look silver like the 1943 nickel I have does.  

I think 1943 to 1945 are all 35% silver. 1942 it was a mix. Not sure how exactly to distinguish, their weight and diameter were same. Maybe a good visual ?

Use the Numisdoc on density test, that should give you an idea.

The silver has a large mintmark on the reverse, above the dome.
https://en.numista.com/catalogue/index.php?r=&c=&cc=y&cn=y&cu=y&cat=y&mode=avance&p=1&e=etats-unis&d=&km=&i=&v=5+Cents&m=&a=1942&t=&dg=&w=&g=

Ah, thanks Manx, I have a sneaky suspicion it's the plain nickel one as it doesn't "look" silver.  I'll have a check when I get home.