You will not be able to sell forged items to NPC's.
Official Reply from CM's:
Another question, If I upgrade a blue robe, classification 2 to tier 2, and I accidently have this in the bag when I go sell djnn loot. Will it be considered as a base item to the npc and sold at base value?
It is not possible to sell items above tier 0 to NPCs. 1
Source:
1. https://www.tibia.com/forum/?action=thread&postid=39254150#post39254150
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