BEFORE PC's latest firmware update, I would just close the Gem.
NOW, however, since that update, which is proving to be a massive battery drain, I am switching the Gem's screen off via Fn + Esc before closing it.
And, by the way, I set the screen's time out to 1 minute of inactive use.
Only time will tell if those tweaks lessen the battery's sieve-like draining.
Cheers.