Question about item quality

I understand quality increases dmg and Stat rolls but I was wonderin about how it is done? Say I have a 0% quality and use a crystal up upgrade the quality will the dmg of the weapon go up automatically or will I have to use some other crystal to get more dmg? Is it worth it or better to just farm for a higher quality version?

The base damage of the weapon will increase automatically.
Its better to farm the crystals and manually upgrade the quality on an item you are going to stick with.