Pie chart uses a single series of data. Multiple series of data can be defined and are each displayed in a separate pie chart. Do you mean you want each Pie Slice in different color? If this is your requirement then you can tailor the look of each pie slice individually by working with the pie chart series appearance property. You can find more information in our help topic - http://www.telerik.com/help/aspnet-ajax/understandingtypespie.html.
Here is how to set Solid Red Color to first slice:
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