One of my favorite materials to use is PearlEx pigments by Jacquard Products (www.jacquardproducts.com). These opalescent pigment powders can be mixed into any medium including acrylic paint, clear acrylic varnish, gel medium or even water. Or, you can use them straight out of the jar by themselves, brushing them gently onto any surface where you want to add a little sparkle and shimmer. My favorite colors out of the dozens available are Pink Gold, Duo Green-Purple, Antique Bronze and Pearl White. I use PearlEx throughout my work, even incorporating them onto the pages of my altered books.