How do I spend just 10 gems, everything is much more and I’ve only got a few!?

When the bucket and the knife block are recharging you can skip the short wait for 1 gem on the Bucket and up to 4 gems on the knife block. If you want to spend exactly 10 gems you can skip the wait on knife block twice and the bucket twice - or skip the bucket wait 10 times but this spends a lot of energy because of how many items the bucket gives out before recharging.

It gets easier to waste (I mean burn) 10 gems once you get the Kitchen Robot and Museum Audio Pass. After a handful of taps, it’s anywhere from 4 to 1 gems to speed up the cool down period. The Kitchen Robot comes from the Restaurant and the Museum Audio Pass comes from the museum. You unlock those locations in levels 25ish to 35ish.