If diamond id the hardest metal, how come in minecraft it is better than gold?

Diamond is not a metal fool, it is a mineral, its a ROCK!

Gold is actually more effective than diamond in Minecraft, but does not last as long. Contrary to popular belief, diamond is not the hardest material in real life either.

Diamond is not a metal. Everybody knows that adamantium is the hardest material.

If diamond is stronger than gold then why wouldn't it be worth more.

Well the two are different.
Diamond is a mineral rock, while Gold is a metal.
Gold does not last as long as diamond does, but is more useful. In the real world diamonds are worth a lot more than gold so i would assume that maybe diamonds, since they are harder, are better.

Mine craft is a game. Toilet paper could be used as money if a game designer chose. Like others said, diamond is a rock, not a metal, and considered more valuable in real life also. Gold is a very soft metal.