How to Get and Spend Rubies(Gems)?

Gems are the most important resources of Celesta - Broken Sky, despite of apparent abundance on beginning of the game, it becomes very scarce on late game specially for players who are striving to get to the top on WB and GR. Its very important to maintain a good supply of gems through of the game.

Where to Get Gems?
On late game most of player's gems should comes from World Boss and Guild Raid, its very important to get a high rank.
 * Tower (early game Gem source)
 * Leveling up (early game Gem source)
 * Diary Login
 * Achievements: Rank up Items and Heroes, Reincarnating Heroes
 * Leveling heroes to max for first time
 * World Boss
 * Guild Raid
 * Recommended players level ups
 * Recommending another player (only 1 time usage)
 * Buy Monthly Gem Package
 * Buy Gems with Money

Spending Gems

 * Buy Adventure 5 times per day - 100 (50) Gems
 * Buy Boss keys 2 times per day - 20 (10) Gems
 * Buy Weekly keys 2 times on Friday, Saturday and Sunday. - 10 Gems per day
 * Buy Elite Dungeon Reset 1-2 times per day - 10-30 Gems
 * For Fantasia Heroes, its worth to buy Boss keys 3-5 times per day.
 * Buy purge/auto tickets if needed

How to save Gems?

 * Instead buying purge (auto) tickets, one can use macro (ex.: Hiromacro app for Android) to automate dungeons.
 * Avoid buying items and heroes with gems on store (even if there is a 10-20% discount)