Is there a way to add shine to a chocolate coating after it has hardened? My recipe calls for melting chocolate chips and pouring the liquid chocolate over the cake for a coating.  That works but, when it hardens, it returns to that dull gray/brown color of chocolate chips, i.e. to the color of the chips before they were melted.

Is there a way to polish or add some shine to the hardened coating?  Would rubbing a thin coating of butter on the surface work?
What you're looking for is 'tempered' chocolate.   Tempered chocolate has that sheen and snap to it.  When properly heated and cooled, the cocoa butter in the chocolate formed the correct crystalline structure for this to occur.  When the process is uncontrolled, you get dull chocolate that doesn't snap quite as well. 

There's a few (1,2,3) different ways to do it.  But overall the easiest way - in general terms, is to heat chocolate to the correct temperature (check the links for correct temperatures for your type of chocoloate), stir in *pre-tempered chocolate (from the store or such) as it cools, and then slightly reheat.

Or, buy a tempering machine.

This should give you that gloss your after.



*Store bought chocolate is pretty much always tempered and the dull gray of the chips doesn't mean its not tempered - just scratched up.  You can use this to stir into your cooling chocolate at step 2.