Diamond prices are down 60% since a 2011 high, and they are still falling. It's not all down to lab-grown diamonds, demand is down too, especially in China.
No one can lab-grow gold yet, so its rarity and scarcity protect its value, but that will end too. It's just a question of when. China launched an asteroid touch-down mission this week, which will make it the 4th country/region to do so, after Europe, the US & Japan.
How soon will it be feasible to mine asteroids? Who knows, but a breakthrough in space propulsion might mean the prospect happens quickly when it does. It's possible gold has twenty years or less of being high value left.
The $80 Billion Diamond Market Crash Leaves De Beers Reeling
Zero G?
Creating a debris field in orbit? You want this thing fully enclosed before you start messing with it in ways that cause it to break up.
I suppose in a very low orbit you could consider messy options if it will all burn up in a few months. But doesn't seem ideal.
What about those things require any g?
Asteroid miners are going to have more in common with spiders than anything else; find a tasty roid, wrap it up in cling wrap and set off bombs inside of it until it's a bag of gravel, then get the whole mess spinning and just let go of the stuff you don't want to keep. Hell when you're done you can re-harvest the angular momentum to propel you over to the next roid and start the process over again.
So easy, why hasn't anyone done it already????
I mean, most space travel ideas haven't been done, even ones that are many decades old. Shit's expensive and risky, both as an investment and an activity.
For the same reason most other things involving space haven't been done yet. We as a species suck at prioritising stuff and allocating resources
Why would that be a problem? The drilling platform would have to be tethered to the rock, but that's doable and I'm pretty sure they drill all the time on the ISS. Actually, didn't we drill into a comet or asteroid for samples sometime recently? The explosives would require no modification at all.
That would be the start of a solution.
Barbed harpoons were the approach with the comet. Putting a band around the whole thing could also work for a small body. If you're going for gold, the asteroid is also going to be paramagnetic if I'm not mistaken, so you can just electromagnet on.
It's slightly more problematic than on Earth, but I'm basically going to need some citations if I'm ever going to believe it's sticking to the chosen landing site that's the hardest part. A lot of proposals sidestep on-site processing, even, and rely on delivering a whole small body to Earth.
Maybe not to Earth (unless you wanna crash economies), but a LaGrange point would be suitable – as well as a place for something spinning so the hairless monkeys could have a semblance of gravity.
If you have human miners, anyway.