Donut charts were formerly separate charts, however it's now simply a variant of the Pie chart.
<script> window.onload = function () { var data = [45,57,48,32]; var donut = new RGraph.Pie('myDonut', data); donut.Set('chart.labels', ['Jan', 'Ben', 'Mark', 'Lucy']); donut.Set('chart.linewidth', 5); donut.Set('chart.strokestyle', 'white'); donut.Set('chart.tooltips', ['Jan', 'Ben', 'Mark', 'Lucy']); donut.Set('chart.variant', 'donut'); donut.Draw(); } </script>