I think there are three ways to use the Gelatos in order to give you different effects. The first way uses a soft paint brush and water and gives you a lighter color.
If you have time please head over to my blog for some other tips and recommendations on using Gelatos: http://delightfuldesignsbykatherine.com/blog/?p=1195
Here's the full set that I purchased which has a wide variety of colors and comes with a waterbrush.
Have a crafty day. Katherine S DT