is one way to lay out and cut sheets of clay to blend one color into another.
Click on the picture to go to a page that has only the template on it.
(saves ink) There is another template for multicolors on this
If you want the two colors that you're starting with to comprise a good portion of the coloration, arrange your layout like this. With this particular combination, which I've kept light to save you some ink, you will have a lavender to very pale lavender and then white. If you don't want much true white in this mix, arrange the diagonal cut line from it's present starting point up at the top left and bring it all the way to the lower right corner, or even a little above it. If you were using a deep purple, the gradation would be much more dramatic.
Assuming that the fold line is along the black line across the middle, you can see how the area
outside the green lines will not be mixed with any color but itself.