I hate gems.
Hi guys, waaaay back when, our cash was like this: We had soooooooo many Lingots. Soooooooooo many in fact, that we all had nothing to spend our wonderful red diamonds on. Duolingo could have easily made more things to spend our bread on. But noooooooooo! Now Duo did this to us: So why duolingo, did you take our Lingots?!? Will it help your income? No. Will it get more users, therefore more donations, therefore more money? No. Just please, give us back our lingots!! PLEASE
I think this describes adequately what Health and Gems are: https://www.duolingo.com/dictionary/Russian/%D0%BF%D0%BB%D0%BE%D1%89%D0%B0%D0%B4%D1%8C/4e5d402172b268f6a72c1a21fe355724
(click on Audio)