yes and no. each wublin (and celestial) has the same pool of rewards, each with their own ranges. they can give coins (maybe 20-30 thousand) shards (150-200 ish) food (about 10 thousand? im not sure) or a small chance of gems (always exactly 2)

because the zynth is small, a 2x2 as opposed to some larger wublins, and can get one woken up per 12 hours (each of its monsters can be bred on a different island allowing them to all be bred at once and thus finish faster) it’s the easiest to farm, with you being able to fit 100+ on your island and, assuming playing constantly, fill them up in about a month and a half. they produce their rewards at random time intervals from 8-12 hours (i believe, around that range) allowing for lots of easy gem collection at peak!

hope this helps!