Iirc correctly

- Exogem tools have an effectiveness of 42%
- Level 1 Quirk Boon gives 400 base points
- Level 2 Quirk Boon gives 1000 base points.

In theory you get 800 points from using boon 1 on gem, and 420 points from using level 2 on Exogem tools.

Therefore the cost needed to only get 1 Exogem tool boon to level 10 is roughly twice as much in terms of stability and materials vs getting 1 Gem tool boon to level 10, however because were only getting one boon to 10 as opposed to 3 it ends up being only 2/3 as expensive (when looking at stability and boon material cost)

Obviously more needs to be done to reduce quirks and to account for the extra vigour cost, which is where the extra 33% comes in to equate to a similar cost.

Of corse this is all in theory - bad rng and boon points going into unwanted boons can make it cost more, but even at double the cost of forging + time spent it would probably put it at around 20k if all goes well.