# 3D bubbles 
Gradient fill is a good choice to visualize depth and volume. In this demo, a radial gradient is used to mimic the shape of planets, and help users to better understand and link the charts to the real world. 

####  Tip
Use the [radialGradient](https://www.highcharts.com/docs/chart-design-and-style/colors) option to set up the gradient effect.