Cascade is using a gross estimate where 14 times one quarter is about the silver content value, that's why you're asked to take the total face value and multiply by 14 and compare that number to the number of dollars you paid.
Anyway, nice find! And as the gold price is now going to unknown places (mainly due to the Brexit and the uncertainty it gives, I believe), I guess silver will follow. Even if you bought it as junk silver, you'll be good in a (short?) while, as you paid close to spot price.