Really??! It's just a big stone. Give that diamond to us speculators, and we will find it's value. We will bid and ask different prices, but we will find the value. We don't really care about the value, but we will find a Price. Price is what matters to speculators.
Why is a diamond valuable? (Actually, why is anything valuable?, but we will address that bigger question later.)
When we were kids, we used to collect those nice smooth or shiny pebbles, didn't we? And cry if we lost a pebble, fight for it, protect it, steal it? But then we grew up..... and realised that stuff wasn't worth much.
Guess what. Mankind still has to grow up. We still strive to own these useless pieces of stones and metals (they do have industrial uses and we can throw them at wild animals when they attack us, but that is not what we value them for).
Settlers could rob natives of things like land and country (and people/slaves), in exchange for bright beads and clothes, because the natives valued those beads... and not iPhones. Unlike those natives, we value money, those pieces of paper, metal coins, IOU notes, virtual money (as if the rest is not virtual), because we believe a goverment or something has guaranteed their value - when most of the time there are no assets to back them. Random names/places/animals/things are valued, and sometimes worshipped.
Monkeys don't value those stones as much as us. That gets me thinking... maybe our society/civilization is built or based on stuff that I think don't have value. Don't we value our culture/civilization? If we stop valuing a random stuff that we value now, then that basis of our society/culture/civilization will change.
Diamonds and modern art will continue to be valued by society for more than a generation. People who fight to own them will not appear as silly as the children who grew up, because society will not grow up enough in their lifetime. Could the value disappear in a generation?.... then they would look silly like those who were in the Tulip mania or Dot Com mania or the craze for a Justin Timberlake ticket?