system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Are all gems hoarded by companies like diamonds, or are there some which are genuinely valuable and rare?
gpt
Jadeite, red diamond, blue garnets - there are some gemstones so rare that you can count the number that exist on one hand. These are super expensive and definitely not stockpiled.

But as a general rule, unless you're super rich, if you or anyone you know has ever owned a thing, that thing is incredibly common.