I've been having fun again using iridescent titanium white and iridescent medium, painting over dried texture paste (all acrylic at this stage). What's particularly interesting is how the texture paste influences the shininess. Viewed from the side, you can see how where there's paste, it's matte. Ultimately using a satin (semi-gloss) varnish will help retain this different.
Get yourself some: choices include iridescent white oil paint (Buy Direct), iridescent oil paint sticks (Buy Direct) and oil pastels (Buy Direct), iridescent acrylic paint (Buy Direct) and acrylic medium (Buy Direct), and iridescent watercolor medium (Buy Direct).
Image: © Marion Boddy-Evans. Licensed to About.com, Inc