Reference article
Red Gem (Duck Life 9: The Flock)
This can power up a lift in Cloud Kingdom
Obtaining
Talk to 
Geoffrey in 
Cloud Kingdom for the first gem. Collect more while exploring Cloud Kingdom. The four gem events are finding the first gem, searching the storm cloud, defeating 
The Cloud Princess and beating 
River, 
Boulder and 
Glyde. The first three completed events award Red Gems.
Using it
Bring a Red Gem to an ordinary cloud lift to power it. The gem is used up, and that lift stays unlocked. The fourth gem reward is a 
Golden Gem for the tournament lift.