Does anyone know if you can mix pearl dust directly into buttercream and have it be sparkly?

unfortunately, mixing the dust with icing will only produce color, no shine.

Thanks! At least I won't waste a bunch of it trying.

You can use luster dust with buttercream if you put the buttercream iced cake, buttercream rose, buttercream iced cookie, etc. in the freezer, just long enough to make the buttercream really cold. Then brush the luster or super pearl dust (I prefer super pearl dust, color the icing whatever color you want, then use super pearl dust) on the cold icing. If doing roses, only take one out at a time, brush on the dust, then take the next out. Work quickly because the buttercream softens quickly. With the cake, you will need to keep putting it back in the freezer as it is a big area and only a bit may be brushed at a time. I've had great luck with super pearl. The reason I don't use the luster colors and color the icing instead, then brush with super pearl is because the colors of luster dust can look splotchy.