Some items come in game with a blue astral and/or immortal on them. You can also buy astral and immortal stones with silk from item mall. There is no corresponding tablet in game itself.
If you have a very nice item you can ask a good friend or your guild manager (if they use silk) to add those stones and pay them with ingame gold. You hand the item over, they put the stones on it and return it.
Luck tablets don't exist in game but you can get some as reward during special events or by voiding items with blues on it. An item with 2 blues and degree V or higher gives a stone when you disassemble it and sometimes it's a luck stone.
