Use gems to shorten build/upgrade time.
Example:
A building needs 500 gems to complete a build time of 24hrs, you only have 50. So you can use your 50 to knock a small percentage of the time off - 500/50 = 10%, so it knocks 10% of the build time, 2h24mins off.
This is opposed to waiting for the counter to get down to 50gems being required to complete the build and letting us knock the time off whenever we want.
