Donut with radial gradient
Radial gradient modifiers
amCharts 4 can either use full-fledged gradients or “gradient modifiers” as a fill for just about anything.
A gradient modifier is an easy way to automatically create gradients out of the plain fill colors, for an instant stunning looks of the charts.
Legend
Adding legend to the chart is super easy: you just set legend property of the chart with a new instance of Legend.
The chart will take car of the rest, creating a legend with items for each slice and toggling/hover functionality.
Demo source