[cryptoz]

> Meaningful quantities of useful Diamonds are not going to form outside of significant gravity wells so 'asteroid' mining of diamonds is a waste of time.

Meaningful quantities of helium are not going to form outside the center of stars. But that doesn't mean the universe isn't littered with it due to star explosions and such. There's plenty of reason to think that diamond will exist in places that it didn't originally form.

[sageikosa]

Helium also forms during alpha decay, perhaps not in meaningful amounts to the grand scale of things, but significant to Earthbound helium production, since 99% of it comes from this source.

[Retric]

Let's put this another way, the average jewelry store probably has more diamonds over 1/10th carrot than the entire asteroid belt. They can form from impacts, but without significant pressure they turn into other forms of carbon fairly quickly on geological timescales.

As to helium, there is plenty of it on earth to do all sorts of useful things.

PS: Yea, that means diamonds are not forever.