How diamonds work
The second currency, what it is only for, and why saving it early is a trap.
Diamonds are not a better kind of cash
Cash and diamonds do different jobs and do not convert. Cash buys the rake, blower and bag upgrades that clear the yard. Diamonds buy class rolls at 40 a go, and nothing else you need.
That separation is the whole design: your clearing power and your class are on two different tracks.
Why hoarding diamonds early is a mistake
A class roll returns the no-bonus Starter Class 40% of the time. So sitting on diamonds waiting to "afford" a specific class does not work the way saving normally does — you are not buying the class, you are buying a lottery ticket, and the ticket price never drops.
The class odds page works out exactly what that means: Bag Specialist averages about 5 rolls, 200 diamonds. Handy Man averages 50 rolls, 2,000 diamonds, and you need 114 rolls before you are 90% likely to have seen it.
The practical answer
Roll when you can afford it, take the first non-Starter result that helps your bottleneck, and put your attention back on tool upgrades. Diamond Treasurer is the one class that makes future rolls cheaper in real terms, because it raises the rate diamonds come in at.
Run the numbers for your own target on the class roll calculator before committing to a chase.