I wrote a short story about trying to mine a diamond asteroid

"arced past Venus ... roughly 159 million miles from Earth, a bit too close for comfort" means Earth and Venus were at opposition.

That is, the furthest they can get apart is when both are at aphelion and at the other sides of the Sun = 94.51 million miles for Earth + 65.36 million miles for Venus = 159.87 million miles.

This isn't "too close for comfort" - Venus will be behind the Sun. I calculate the maximum visible distance for Venus is 156.6 million miles. No one will be able to see it, much less target it from a laser in Earth's orbit and have the refracted light visible on Earth.

> giant satellite laser beam

Laser beams spread ("beam divergence"). When we use lasers to measure the distance to the Moon, it's widens from a few meters to a couple of kilometers. A space satellite will have to be very large to give a narrow focused beam across millions of miles - which is hard to hide. Only a small part of that beam will hit a 5 meter long object. The light reflected/refracted from that will not all go back to the Earth.

The amount of power needed for that reflected laser light to blind people on Earth, or to cause after-images, is incredible. And very expensive.

> the systemic risks induced into the diamond market by an extraterrestrial diamond asteroid

I assume synthetic diamonds will be even easier to produce in 16 years.

If I get the numbers right, about 140 million carats of diamond are mined every year, and 14.6 billion carats of (mostly industrial diamonds) synthesized.

FWIW, 0.2g * 140 million carats = 28 tons, or @ 3500 kg/m3 = about 8 cubic meters.

> big enough chunks would break off for his robo-space-vacuum-drones to slurp up

The diamond is in a hyperbolic orbit, so at solar escape velocity. How do those drones capture the chunks and have the delta-V to bring enough diamond back to affect market rates?

The outcome is interesting. I can easily interpret it as a form of environmentalism commentary, following the long tradition of SF being a form of commentary about the present-day.

So, what about making it a fly-by, a few Moon distances from Earth. Rüst could be a trillionaire with a personal SETI project to send laser messages to other stars. (With government interlocks preventing him from pointing it towards Earth.) And the diamond could be an alien space probe, activated when hit by the laser. That would hand-wave the tech needed for the shimmer.