I'm wondering if there were contaminants on those particular nickels. It doesn't really look like toning, it looks like there's crap on them, sort of.
It's not strange at all, rather it is expected. To start with every coin is unique, so it is expected that they will not all react the same. Also you have to take into consideration what might have happened to those coins before your father ever got them - that too is often unique. And when it comes to coins toning or not toning there are a thousand variables involved.
I bought a few sets from north west Arkansas were my father-in law lives that were beautifully toned, mostly dimes and half dollars, but I had some trouble getting them graded by NGC. The coins that were stored in bags in safety deposit boxes with no moisture control were junk after so many years of not being stored right.
I agree it does look like 'crap' -- esp. straight on... but when you angle the view different colors come out. It's strange, don't like it much...
Strange. By the way, I wasn't being condescending with the word 'crap.' But I imagine it probably does look different in hand. I would say maybe switch those coins to a different album or something, maybe. Maybe it has something to do with that case they're in.
It has to do with the content of things nearby (like paper/cloth with a high sulfer content), CLOSE but in many cases not touching the coins that end up toned nicely, along with the humidity, and whether the coins are moved frequently or not. In many cases the coins have to be a certain distance away from the "source" but not too far away, and not too close either.
