It really depends on the context of the book you are reading.
I would say it either means a mountain that was full of diamonds or a woman who's baby is going to make someone extremely rich.
A lot depends on the context. If you are talking about a geological feature, such as a mountain, that contains diamonds, it places the diamonds on a highter, even a more animalistic, level. The diamonds become "life" to the people who will benefit from them. As when people are born, people's lives will change when the diamonds are mined.