I don't believe diamonds are as rare as the public thinks.
Up until 50 yrs ago they weren't nearly as valued as they are today.
Debeers would have you think otherwise
The whole Debeers marketing of you have to give a diamond to a woman as "diamonds are a woman's best friend" and other marketing ploys made it seem diamonds are for rare occasions, and therefore a diamond is rare. You have diamond mines in Ghana and many other African nations. In Russia, etc. and let's not forget that we have man made diamonds that are so good now, that it is really hard to for an expert to tell the difference.