I feel like a total noob asking this question but it's an honest question and googling the answer or asking global chat has proven difficult.

I recently decided to try the zoomancer build as I've never played a necro before and it looked fun to have a million minions on the screen, one of the uniques it uses is the hungering loop with animate guardian as the main skill. the thing is however I learned the hard way that I can't just socket already level 20 gems in there they need to be level 19 and then become 20 and the quality doesn't matter.

so my question is how do I level these gems up quick? I guess the same question exist for alternate types of gems like awakened or divergent etc.

any tips on how to do this are appreciated thanks!