Evolving you gear is a tedious process that will require a lot of gear to be used to increase your chances to hit the next evolution level as well as a lot of Jewels of Evolution which can be purchased for 300 garnets each.

This is where having alt accounts can really come in handy to be able to farm garnets and gear to feed to your main account. 

Upon hitting certain evolution levels you will gain a Star and this star is a constellation point which will be used to unlock additional stats for your character. These are essential for establishing the ground work for your build as they will provide stats you will not find a lot of throughout your play through.