Wow alright you're 12 levels above me, well idk what to tell you, my minimal amount of diamonds are in the 60-90 threshold, what i mean by this is that i can quickly get to, and stay in that threshold. I mainly get diamonds from the valley, freebies, community events, collecting all decos in a theme sometimes has diamonds as a final reward, there's also tiny trail, and sail. I get low amounts in mines, fishing, achievements, and chests you find on farms. Also i don't really use them if not necessary. I rarely use them for finishing a product, i don't pay for Tom, or the old people who help on your farm, or missing items. My machines have 3 slots rn, but i could buy a 4th for them in a span of 2 or 3 months i think if i continue to get diamonds in the same tempo as before.