Are moon rocks more valuable than diamonds?

The answer depends on comparing two specific items: a moon rock and a diamond.

Comparatively, there are many answers to your question. Each has to do with the composition of each item.

For example, diamonds are valued by their cut, clarity, colour and carat weight. Moon rocks are valued another way.

You can buy a 'moon rock' today for about US$45; you might find a tiny diamond for sale at that price, but more likely, you'd pay more for a diamond than for a moon rock if each item were the 'same size'.