Gem leveling for that +20% quality goodness

Ok, so you hit 20 on your gems and your guide says they all need level 20+ plus 20% quality.

Do you do the trade trick and keep playing on maps with level 1 20% quality gems and farm gem xp at lower levels, or... or what?

I know to level up 6 in off hand, one build I am following says to level up 6 arcs in off hand to roll for a higher level later.

I haven't sacrificed a level 20 gem yet and am wondering how best to do it. cause the gemcutters prisms are expensive as well.

I would think making a lv20 gem into lv1 20% would break the build, at least at that level of mapping.

any advice appreciated, thanks!

If you have enough GCPs, just bring it up to Q20 and vaal it.

If you dont, but have a 2nd lvl20 gem ready to go, use one for your main setup and flip the other to 1/20 and relevel it.
Getting into the lvl15 range wont take long, if you are consistently farming t10+ maps. Maybe a few hours.
Honestly its just the final push from 19 to 20 that takes time.

Also it depends whether its attack, spell or support gems.
Attack and support gems can just be flipped and leveled again. No big deal.
Spell based gems however are different, because the base dmg very much depends on the gems lvl, not so much on weapons and such.
So be careful about active spell gems. The rest, as I said, can be flipped asap.

Thank you, this is what I gathered, but thanks especially for the spell gem advice, I wasn't thinking that.
Just don't want to break what works well :)