In Known Only to Kings, I give a brief description of what we currently believe about how diamonds form. As I said, there is a lot we still don’t know about it, and if we did know more, it would probably be easier to find more deposits. Kimberlite and lamproite pipes aren’t the easiest things in the world to find, knowing more about their formation process would surely help us find more of them.
Here is an article published by the Gemological Institute of America, which gives a lot of additional information. It’s not too technical if you persevere with it. There is also a more recent 32 minute talk, which becomes technical quite quickly, but if you read the article first, it might help your understanding.
I find with technical stuff it’s best to let it wash over and catch as much as you can. Eventually, you get to understand the words they’re using. It’s a bit like learning a new language.