High Quality or just HQ items are highlighted with a golden shine on the icon and with a symbol in text. All craftable gear, meals, medicines and intermediate materials exist in HQ variants. HQ items may not stack with normal quality ones in inventory.
HQ items are crafted by increasing the "Quality" bar to its maximum by using Touch actions whose effectiveness are governed by the Control attribute. They function the same as their normal (NQ) counterparts but convey extra benefits. They also provide double rewards when turned in for Grand Company supply missions and levequests.
You may irreversibly downgrade an HQ item into a normal quality one via an option on the right-click menu.
HQ gear has much better stats than its normal (NQ) counterparts. This is particularly evident after level 50, when stats start to get large. NPC vendors only ever sell normal quality gear. The sole source of HQ gear for gil is from other players via the Market Board. Players will also receive HQ leveling gear directly (and in coffers) from the Main Scenario Quests and certain Side Quests.
For endgame crafted gear, meals, and medicines, only the HQ items should be used to participate in current high-end duties. (NQ items have a 10% penalty in stats, which is like being ~20 item levels lower)
When used in crafting, HQ materials provide up to a 50% bonus to the starting quality bar, depending on how many HQ mats are used. The degree to which 1 material increases the quality bar is different for each craft depending on the recipe.
For each gathering attempt, there was a chance that the item gathered would have been HQ. This chance was modifiable through specific actions.