In the shop at the bottom there are three gold chests you can get with diamonds.
The middle one is 600 diamonds for a chest that (supposedly) rewards between 8250 and 30000 gold. I have purchased two of these and both times got the minimum amount of gold, 8250.
Either the range is broken or you are deceiving players by showing an open range that is actually weighted. Or I am just incredibly "lucky" and should play the lottery.