Very occasionally when you synth an item you will notice that the animation for synthing it is slightly different and the result of the synth will be a high quality version of the item. The chances of a high quality item are pretty rare, but the chance of HQ goes up with the amount of levels you are above the cap of the item.
Generally there are 3 tiers:
11 tier (10% chance of HQ), when you are 11 levels above a synth you have a 10% chance of a HQ item.
31 tier (30% chance of HQ), when you are 31 levels above a synth you have a 30% chance of a HQ item.
51 tier (50% chance of HQ), when you are 51 levels above a synth you have a 50% chance of a HQ item.
Basically just synth like normal and if your lucky you will get a HQ and the chances are better if your over the skill cap of the item.
good luck with your HQs!
