So, you want to know how to make/use gems to their fullest potential. This guide is for you, then!
Gems. They're not important at a glance, but when closely examined, their true potential is revealed. There are three types of gems, warrior gems, health gems, and wealth gems. Each one has different uses. To unlock gem slots, you must pay 1000 mirian per gear piece. To get the mirian, there are other guides that go more in-depth on that. This guide, however, aims to introduce, or help guide gem production.
Warrior gems are the damage gems. They make your weapons do more damage, based on the rarity, and if put on weapons. They make all of your weapons do more damage when put on armor, however not as much as when a single gem is placed on one of your weapons. Finally, they make your followers do more damage when placed on a rune.
Health gems give you more health, and, like warrior gems, give different bonuses when put on different gear pieces. When put on a weapon, they increase the amount of health stolen with the weapon that they are equipped upon. For armor, they increase your maximum health, and for runes they decrease the amount of damage your followers take.
Wealth gems are gems that provide bonuses that profit you, as they are 'wealth' gems. When placed on a weapon, they increase mirian drop chances from that weapon. When placed on armor, they increase your total xp gain. Lastly, when placed on a rune, they provide up to five levels on newly recruited followers.
Okay, with the bonuses of each gem out the way, let's get to how you farm gems. Gems can be obtained in three ways. The first way is through treasure orcs, which is generally the easiest way to find them. The second way is through randomly wandering through the world and finding gems laying around. The last way is through Shadow of The Past missions, which are only obtainable through completing all three objectives and can only be obtained once. For this guide, treasure orcs are the method that is going to be used. There are two types of treasure orcs. One is the usual orc with a white marker above their head that drops basic gems. The second, on the other hand, are treasure ologs, that have a red marker on their head that can drop either 1,000 mirian or a Polished gem. Treasure ologs are rare, so you'll generally go through the world only killing usual treasure orcs.
Gem tiers provide the multiplier for their bonuses. For example, a regular warrior gem provides a 10% boost to a weapon, whereas a perfect warrior gem provides a 30% boost to the weapon. The regular tier of gem is the most basic and can be found by killing usual treasure orcs. The second tier is carved gems. Carved gems can be found by killing treasure orcs, too, however it is a lot rarer. They can also be found by combining three basic gems. Polished gems are the third tier of gems, and they can be found by killing a treasure olog or combining three carved gems. The fourth tier of gems is refined gems. They can only be made by combining three polished gems, however the result is very much worth it. You might only get these late act II or early act IV. The fifth and final tier of gems is perfect gems. They are only obtainable through combining three refined gems. These gems are incredibly late game items, and you will generally only get them in late shadow wars.
Combining gems can be done by going to the gem screen and hovering over a gem. If you have three of that gem, you can make a better tier gem. It is highly recommended to not do this when you don't have to, seeing as you can end up with a shortage of powerful gems to give to armor/weapons/runes that you haven't paid attention to. For example, you can rush making a perfect gem for one gear piece, but then only have carved gems of that type for other pieces of gear.