ChartFillFormat Object
Represents fill formatting.
Using the ChartFillFormat Object
Use the Fill property to return the ChartFillFormat object. The following example sets the foreground color, background color, and gradient for the chart area fill in myChart.
With myChart.ChartArea.Fill
.Visible = True
.ForeColor.SchemeColor = 15
.BackColor.SchemeColor = 17
.TwoColorGradient msoGradientHorizontal, 1
End With