Hi Sara V,
I’m not sure I understand your question, but, if you haven’t already, check out CODAP’s bar charts as shown in the accompanying screen shot. They aren’t colored by a gradient, but they do show two different ways to think about part and whole.
The second screen shot shows that you can use a gradient to color bars (and points). But I was disappointed that the result is not smoothly uniform from light to dark.
Does that get anywhere close to what you were thinking about?
Bill
p.s. No pie charts in CODAP.