Gems are very important in Pokemon Duel as it is the main currency used in the game to purchase Booster Packs and Plates, as well as speeding up Time Booster. Yes of course you can use cash to buy gems, but why do you need to spend on it while you can get them for free? Here are some guides to help you earn gems without paying your cash!
As you can see these gems purchasable items gives you Pokemon Figures and useful Materials. I do recommend you to farm and spend all of your gems on the Sextuple (6-pack) Booster Packs as it is guaranteed to drop at least an EX-rare figure.
So there are the few ways where you can get gems:
Collect your daily login rewards
Free gems are given everyday when you login. Remember to check your inbox messages!
Complete daily missions
Completing your Daily Missions will reward you with Pokemon Duel Gems. These daily mission comes with a set of % of awarding gems and will refresh every 24 hours. There will be 3 missions everyday. When you completed 10 missions, you will unlock a Special Mission which rewards you an access to Special Wheel Spin with chance to get even more gems.
Complete Quests from Story Mode
There is a single player Story Mode in game where clearing a stage give you some rewards depending on the color the roulette wheel landed on. Those stage comes with 3 extra challenges, rewarding you a gem whenever you complete one of it. That means a total of 3 gems are available to grab in every Story Mode stage.
Well this is the end for a little guide of earning free gems. Good luck, have fun!