What's the easiest way to get gems for free?

Social Point actually gives more opportunities than most gains to earn in game currency (gems). The easiest way is to just play the game every day and resist the urge to spend them on speeding up breedings, hatchings and farmings. Let them build up.

On Facebook there are features Mobil does not have. There is a daily calendar that gives gold, food, and gems. You just have to check every day to get the rewards. There is also a roulette that you can spin once a day that gives you a chance to win 50 gems.

Mobile versions have Freebie Island where you can earn gems by watching videos and completing tasks like trying a new app or taking a survey. Freebie Island offers special promotions that often runs extra videos ar double gems for completing offers. Freebie Island is not without issues however. You have to follow their instructions completely and provide screenshots showing completion of tasks at times. Freebie Island is operated by outside vendors so please review THIS THREAD for more info about Freebie Island.

There are also plenty of opportunities in normal game play through the various quests, league battles, and current event. Best advice, just play the game!

@ColaMelon You get gems from

Freebie island ad's
Jewelem Tower
Daily Shuffle
Level up
Monday Reward
Daily Gift
League Battles
Goals
Earn Gems/tasks
Dragon Card Packs

Mobile users can watch videos for gems in the cinema in freebie island (this is available after you have played DC for 21 days); two videos every 8 hours give 1 gem. (1x3)= 3 gems per day (3x7) is 21 per week! ( every so often we get offers on cinema to watch more videos for gems) - if you have issues with the cinema check the cinema issues file for possible ways to fix it
Jewelem tower (once complete) gives 1 gem per day (1x7) = 7 per week
Daily shuffle on PC (puffin browser app for mobiles) gives you a chance of 50 gems but of course you need to be lucky!
Level up 1 or 2 gems
Monday reward (PC/puffin gives 5 gems when you win)
Daily Gift on PC gives a total of 15 Gems over the 15 day calendar (also small amounts of food and gold)
League battles on mobile give 3/4/5/6 gems for completing the league depending what level you are, on pc/puffin browser you either get tickets to purchase card packs with or gems (temperamental system!!)
Goals to reach in game on mobile and PC platforms give various amounts of gems/food/gold depending on the goal
Earn gems (Tasks on mobile) option is also available on mobiles and PC, you can fill out surveys, download games and various things to earn gems, these are NOT ran by sp and sp are NOT responsible for paying the gems, sometimes you won't get them, sometimes you will, Take screenshots of the requirements before starting these tasks so you can check later you have completed them correctly, I recommend doing the free ones, be prepared for spam if you have to give an email address and note that the game downloads usually require you to play to a specific level in order to earn the gems, they can take a few days to be credited to your account ( if you need to report missing gems do this from the task wall by clicking the ? or missing gems link)
Dragon card packs contain various amounts of gems food gold xp and a dragon and can be obtained for real money only and sometimes when levelling up on PC, it used to be every 5th level but that may have changed.
You can always buy gems of course, I recommend waiting for sales and checking the prices on pc compared to mobiles because they can vary
For breeding tree wait until it is on offer.

How to Get Gems Easy in Dragon City