Burnishing

Burnishing is the process of polishing a surface by friction. It’s really a term that has been borrowed from the world of manufacturing where metal, pottery and even wood is burnished to flatten and smooth the surface often leaving a noticeable shine. In the world of papercraft, burnishing simply refers to the process of rubbing paper or card stock with a smooth flat tool to achieve a smooth, shiny surface. Some paper crafters use the term to describe the action of pressing on a fold to sharpen the crease.

HAVE A GO: 

Try cutting or punching a little butterfly from card stock, then use the flat side of a bone folder or a shaping tool to burnish the wings to a nice shine.