I'm gonna take a stab at your question even though I'm not sure what you're getting at.....
actual gold is tangible. If the market tanked, it could stil serve directly as currency. Whereas owning a certificate for XOM in a grocery store ain't gonna get you much. With that said, many people will assume that owning gold stocks or gold indexes will work as well, but it really doesn't. It's just trading on those who are holding the gold. If the market tanks, gold stocks also won't be worth much.
I had a friend who, as a hedge, bought up silver quarters. His theory, that in a worst case scenario, he could at least buy a Coke. My grandfather bought diamonds during the Depression and actually did quite well for himself. I'd buy diamonds over gold. I also would like to have a windmill in my backyard and solar panels on my roof. Oh yeah, I'd suggest putting in a water tower in your backyard. I think that's the ultimate commodity. JMO