I just tried the 24 hour gold mines again after seeing they were improved with the most recent update. Two of the mines gave me 47 diamonds and one gave me 71 giving me a net gain of 15. It really should be changed to give at least 50 diamonds back at a minimum. Even 50 diamonds is a joke to be honest. All of the other mine options cost nothing and I often gain around 100 diamonds over 24 hours. It doesn't make any sense that a feature you pay diamonds for would be significantly worse than the standard free version.