Skill gems: All these add an attack, spell, projectile, or trap/mine. Support stones: All these gems modify supportable abilities when equipped at Rainbow Six Siege Credits a linked socket (one that has a line drawn to some other socket). The service gem must be compatible with the gem in the connected socket in order to have an effect. As an example, a support gem that affects projectiles won't do anything to a connected melee attack stone. Ensure that your linked jewels are compatible!
Equipped gems also level up as you earn XP, getting ten percent of their foundation XP granted from monster kills. Your personality experiences an XP penalty when revisiting lower level areas, but that penalty doesn't apply to gems. So you can certainly level gems by replaying areas that are a few degrees lower than your existing degree.
Each piece of loot you get takes up varying levels of room in your luggage compartment. To carry as many possible things at once, you have to move items around and squeeze items into the allotted spaces. Even then, your luggage is likely to fill up quickly in the Rainbow Six Siege Credits reddit event that you pick up each and every thing you encounter.
The trick, then, would be to dismiss things that your character can not utilize or are of low price. Item rarity is indicated by colors: White: Norma,Blue: Magic,Yellow: Rare, Orange: Unique.