In this game, there is no inventory management, no items to equip and sell, only permanent equipment that you keep upgrading until it reaches the 10th upgrade tier. In order to upgrade an item you must have enough gold and upgrade gems to fill the requirement. There are three types of gems: weapon, armor and jewel. Each gem is used to upgrade a specific kind of item. Weapon gems or used only for your weapon, armor is used for all 3 three parts of your armor (boots, gloves, body), and lastly, the jewel gem is used to upgrade your three jewels (critical hits, gold, and experience points). You can get gems from the marketplace or from enemy drops.
Your priority in upgrading depends on your needs: those who want to do fast farming through training will want to upgrade the jewels for gold gain and experience points (as it will boost the amount of both that you get per fight). Those who focus simply on combat will want something else –like weapon and armor for well rounded types, or weapon and criticals for those who specialize in dealing damage.
Upgrading the weapon increases your damage vastly, so as costly as it may seem, it is very, very useful. Your gloves increases defense, maximum HP and attack speed –making it a very well rounded piece of equipment. The armor increases max HP by a vast amount as well as your defense, this is perfect for characters designed to take plenty of damage. Lastly, the boots will increase your defense and speed –making it perfect for those who want to focus on making plenty of hits one after another.
For the jewels, there are three types: one increases your chances of getting critical hits (at highest, the bonus is 20%), the second increases the amount of gold earned per fight and the last increases the experience points gained per kill.