Ok.. 1... Level 15 Goldsmithing skill and you want to HQ something that is the same level cap? I'm guessing your new though, so I wont eat your soul and send you to the depths of the abyss to be forever wandering.... Um.. I mean- I'll answer your question.
In order to HQ something, such as the above, you need to be around 31 levels above the cap of the item in question, in order to do it with any amount of consistency. In this case, to HQ this item fairly easily, you should be around Level 46+ in Goldsmithing.