The idea is that they were indeed stolen. Those particular coins from that specific year had never been put into circulation. So, the only way they would have ended up in some individual’s collection is (real) theft.
What is weird is that given who her father was, she should have known.
But otherwise, if you own coins/paintings/whatever that might be valuable, and don’t expect them to be seized, it makes complete sense to bring them all for authentification. After all, having one authenticated doesn’t prove that the others are the real deal too, so if you intend to sell them you want to have them all checked.
My mother owns some gold coins of various origin, and if for some reason I believed they could be rare, I would have them all examined. It would never occur to me that they could be seized. But I would need to have a good reason to assume they’re rare. And again what is weird here is that she knew enough about the coins to believe they were unusually valuable, but not enough to expect them to be seized.
You don’t need to know a lot to expect gold coins from 1933 to be potentially valuable. What she almost certainly didn’t know was that they were as hugely valuable as they were.
Otara
I don’t know. The coins I was refering to are all older than 1933 I think (one is a Tsarist Russian coin, for instance). I don’t expect them to be valuable (well…more valuable than their weight in gold, I mean). For instance, I don’t think that France minted any gold coin since WWI. And those pre WWI coins are the ones you buy when you want to invest in gold. The most common ones are probably those minted under Napoleon III (1852-1870).