http://en.wikipedia.org/wiki/De_Beers
The only reason diamonds are expensive is due to a monopoly by one company artificially inflating prices. It's literally criminal in the US for them to run their company in this manner.
Also of note, glasses/sunglasses (
http://en.wikipedia.org/wiki/Luxottica) and Cheerleading gear(
http://en.wikipedia.org/wiki/Varsity_Spirit) are all ran in the same manner. Although in less of a scale to keep them out of the spotlight.
At least Monsanto fucks your mouth while you are looking at them. Not your ass while you aren't.
So please if you will make an argument using an item of value. Please do not use something that can be made, in a lab (
http://en.wikipedia.org/wiki/Synthetic_diamond).
Sorry for the wiki references. It's my bedtime and I didn't want to do a ton of real research.