I read this article about how advancements in chemistry are allowing scientists to make synthetic diamonds that look just like mined diamonds. Synthetic diamonds are chemically and physically true diamonds, and they cost only about a third as much as the ones that are naturally found. These synthetics have been around for a while, but have only recently been made to sizes of more than one carat. Synthetic diamonds start out as tiny diamond "seeds" which chemists then grow.
Scientists are doing even more with diamonds; they can turn either natural or synthetic diamonds into different colors by introducing chemicals into the stone. For example, diamonds can be turned blue by carefully infusing them with boron.
Not only are these advancements interesting, but they may someday reduce the mining of natural diamonds, which is a harsh and dangeroud task.
Here's the article if you want to know more.