Just do a Text search for 8500, then after you finished searching a popup will appear to change values found similar to 8500, then change the value to -9999999 and click yes.
this will change the value from 8500 to -9999999 in shop and it works !!!
Click as many time you want increase the gems and elixer then revert back the values to 8500 !!
I know this method cause problems to other memory address but i tested it and have no issue regarding gameplay....