Procrastinator wrote:
The main reason is that the total amount of gold in the world is relatively rigid compared to other things. Mining supply is slow and gold is rarely destroyed.
Although I'm speculating a bit about the original poster's question, I think that this answer may be closer than most in getting to the core of what the original poster is wondering, which seems to have more to do with the significance of gold in monetary systems than it does with the value of gold when compared with, for example, the value of Renoir paintings, jumbo jets, skyscrapers, and Super Bowl tickets. If that's what the original poster is asking about, it's actually a very interesting and important question. (On the other hand, if he just wants to know why a bar of gold is worth more than a bar of stainless steel, that's probably a much less interesting question.)