To achieve this 'granite-like' effect, I painted this flourish with black acrylic paint and then applied an uneven coat of Rock Candy Crackle Paint.  The rock candy gives the chipboard a nice uneven texture, yet it is clear so the color beneath the coat shows through.  After the Crackle Paint dried, I misted the flourish with a mixture of black soot Distress Ink Reinker, water and Perfect Pearls.  If using other colors, this effect works best with a darker ink and a lighter Perfect Pearls.  You can increase the contrast of this effect by adding more Perfect Pearls.  You can use Glimmer Mist as well.  Hope this quick tip is useful!  

To see the full layout where I used this technique, click on the link below: 
Goosies (Godsisters)