Fiery armor:the breastplate and the gem \"heart of the dragon\" (Divine Divinity)

Good afternoon. The crux of the matter is that I have a breastplate on which, if you hover the mouse, you will see that its name is:the Silver breastplate. This bib is great:it is intricately decorated and completely useless in battle. But if to impose on him needed a spell... is Gemma heart of the dragon. According to the description in the passage says. that's all we need to bring in the Underground halls of the dwarves the blacksmith and he'll fix them and make one. But the blacksmith does not react to this armor and dialogue about fixing does not occur. Maybe it's not the bib? Then as to put on the conjuring, and who is supposed to do? And how he's useless in battle? It has good performance and plenty of gems you can insert.
Anyone who is not too lazy to answer-thank you!!!