This might not be the most scientific thing in the world, but something I've known for a long time that other people just don't seem to understand is that diamonds in particular are actually a very common gemstone. Sure, they're kinda rare on Earth (although, they are still one of, if not the most common gemstone we've found here), but space is literally full of them. The main reason why they cost so much to buy is not because they're really rare and hard to find, but actually just because people really want them because they think they're really rare and hard to find.

Also, diamonds are normally colourless, and only develop colours if they develop impurities, form with some extra materials, or are affected by radiation. Diamonds which form with nitrogen will appear yellow and sometimes brown, diamonds which form with boron will appear blue (this is why Minecraft diamonds have a bright blue colour), and diamonds which have been affected by radiation, normally in the form of alpha particles, will appear green. Diamonds which experience plastic deformation of their crystal lattice may appear brown, and it's thought that this is also responsible for the red and pink colours that some diamonds may develop. Some diamonds may even appear black in colour, and they simply have numerous dark inclusions. These inclusions are sometimes seen as small dark spots or patches in other diamonds.

...I think that's quite enough about diamonds for one day, but if anyone's particularly interested, I could talk more about diamonds, or some other gemstones. Perhaps I should consider teaching the world about the many wonders of precious stones sometime.

Awesome