I agree that the jewelry-on-little-girls is definitely a cultural thing. I grew up in the same WASP land that Mac (and I imagine Michelle) did, and little girls almost never had their ears pierced. And if someone did, it was like that scene in Friends when Rachel's sister pierces Emma's ears- oh, the horror and judgement! It was something that you begged your parents to let you do, and they likely relented around 11 or 12.
That said, my sister and I did have "real" jewelry. My Mum kept little jewelry boxes in her room for each of us, with a few fine pieces each, most of which were Christening gifts. I remember that we each had a coral necklace, some gold ones, and I had a gold bracelet (that I still occasionally wear) too. We kept our costume/fun stuff in our rooms but Mum was keeper of the nice stuff- which we only wore on special occasions.
I think I'm a rare young person in that I actually like fine jewelry- well, some of it. I like bolder costume pieces as well, but my jewelry wardrobe wouldn't be complete without my pearl studs, gold nugget earrings or emerald ring.