+1 its not rare and it does have has inflated value well marketed.
+2 Diamonds are not rare. Essentially De Beers used to have an near monopoly on the diamond industry. Through clever marketing (such as insisting that they should cost 3 months salaray) and witholding stockpiles of diamonds (artificially creating scarcity), they created a demand with a shortage of supply. Thus they were able to inflate the price of diamonds.
For even more reasons not to spend crazy amounts of money on a diamond, research blood diamonds or diamonds used in the funding of wars in Africa.
Instead, consider a cultured diamond. A cultured diamond is a man-made diamond which is made in the exact same process nature does. Originally man-made diamonds were made for things like diamond tipped blades and other tools. However, the process has gotten so good, now you can get a diamond that is so perfect a gemologist can not tell the difference between a real diamond to that of a cultured diamond. In fact, they are so good, that they have to make a specific mark on cultured diamonds to indicate that they are man-made. They also do not get a GIA report that real diamonds do. You can get a much better quality and size for the same price or basically pay 1/2 the price for an equivalent natural diamond.
Having said all that, as you can see I spent over $12K on a diamond in my post above. Seems hypocritical huh? Even though I don't believe in diamonds and think they are the most ridiculous thing in the world, that isn't how women view it. From what I've seen, many women care more about the sacrifice that a man is willing to make than the actual item itself. Unlike a guy. If a guy wants an Xbox, he doesn't care if his woman spent $1M for it, or it fell off of a truck. As long as he has his Xbox, he's happy. A woman is different. They want to know that you spent the money. So if you could buy a fake diamond for $10 that looked EXACTLY the same as a real diamond, if she knew you only spent $10 on it, she wouldn't be happy. Likewise, if dog poo all of a sudden was worth thousands of dollars and all women wanted one, then if you spent $10,000 on a piece of dog poo, it would make her day. Meanwhile a guy would think, it's still dog poo. Instead of thinking of 10,000 dollars, it's more like 10,000 little notes of "love" or "caring". Each dollar is another reminder of how much you care and the more "reminders" you give her, the more special she feels.