My pets used to give me gems all the time. I could absolutely count on getting one or two (sometimes more) gems a day by collecting regularly from my five pets. It still takes forever to save up for something I want to buy with gems, but at least that gave me a sense of constant, slow progress. The past couple weeks I've maybe been getting one gem every two or three days by collecting from pets 2-3 times/day. I've even noticed that the pets, who most often give 25 coins each collection but can range from 10-200 coins per collection, have more often yielded 10 coins lately. Anyone else experiencing this? Fewer tools and expansion permits from pets, too!
I have, in the past, recommended the pets as one of the best investments you can make to speed up the game and make it more fun, but they've lost their lustre in my recent experience!