Here is a link to an excellent tutorial on the Gamsol magic technique!
Gamsol Magic Tutorials at Splitcoaststampers.
I have only had my prismas for a short time and love using this technique. I know it is widely recommended to get the made in Taiwan blending stumps, because they are firmer and blend the color better. Also, if you can't find Gamsol, look for odorless mineral spirits. Gina K. Designs sells this and you can find it at Michaels in the fine art section (Mona Lisa Odorless Paint Thinner- I think???). I would definitely check out the tutorial, it was a huge help to me! HTH!