Some of them are “seeded.” The Franklin, NC area is somewhat famous for naturally occurring sapphires, rubies and emeralds, with “gem mines’ all around, but there just aren’t enough of them in the buckets of dirt to keep the tourists entertained sufficiently to keep coming back. So, they enhance the dirt with some they’ve bought. Nothing huge, just barely large enough to polish or perhaps have cut. If a patron ever finds a really noteworthy gem, rest assured it wasn’t seeded because they’re just not going to spend that kind of money.
I worked summers in the vicinity while in college. I do recall that you should be careful around known veins with sapphire, the soil can be toxic with long term exposure due to the cyanide present in the peculiar yellowish soil. Cyan, blue, sapphire. Fair amount of fool’s gold around those places too. This was a private site rather than commercial, back off the beaten path on the property of an old resort. Only guests and employees were allowed back there.
We went "gemming" in a couple of places in Franklin and our buckets each had an 'arrowhead' - phony of course, but still a hoot. We kept our "gems" which wifey put into a small goldfish bowl when we got home.
not only the naturally occurring toxins but often the ground has a tendency to be unstable
Seeding happens kind of like shills in some games at the fair. And you are correct if it is a substantial gem or piece of gold guaranteed it wasn’t part of the salting process. But to me it was always great fun and a way to enhance my understanding of the geology of the area I grew up in. I still think it is a good way to teach