Reinforce Reinforce is a very important process if your actually interested in better equipment or weapons. It's advised not to waste money, effort and time into this at lower levels but just stock up till your higher and in more need of the boost up of your equipment.
Reinforce can add stats to an item - Like HP, INT or STR and so on. (See below for more information)
Where is the Reinforce icon?
How to Reinforce? First open your Reinforce icon, Drag the equipment you want to upgrade into the window. Then find the stone you want - Make sure you check you have an ore that goes for the kind of equipment you want.
How many gems do I need? You can use everything from one gem to 100 gems on one item, but IF you repeat the upgrading process on the same item the OLD effect will be erased - It will not stack - Therefor it's better to wait till you got many. On blue (rare) equipment you need HQ gems, 9 normal gems = 1 HQ (you do this through constructing)
Difference on the stats isn't that big, for around 50gem you can get maybe 12 while 100 will be 25. The more gems you use the better chance you have of it succeeding but 100 gems can still fail. Can all equipment be upgraded? No. but most can, you can easy check it by holding your mouse over the desired equipment.