I love using luster dust to add a metallic shine and shimmer to my cookies.  Did you know you can apply it wet OR dry?
It's a little hard to see the effect of a dry luster dust application in photos sometimes. 
Think of it this way....dry luster dust is like a shimmery body powder.  Wet luster dust application is like a gold lame skirt. 
The wet application is perfect for when you want an opaque finish that really transforms your cookie into silver or gold.  These 
First Communion Chalice cookies are a great example...and the 
tutorial for applying is there for you as well.  
Instead of using the wet application for the keys, I kept 
the cookies in the same color palette by adding the luster dust dry.
Adding the luster dust dry lets you see the original cookie color, but adds a sheer, metallic shimmer.  
It really couldn't be easier.  Let your cookies dry overnight, then use a clean and dry paintbrush to brush on the luster.
Can you see the difference? It's a little hard to pick up in a photo.  The cookie in front has luster; the one in the back doesn't.
How about now?
The same luster dust color I used here can be found at 
Sweet! 
Happy lustering!