The array is in a format that can be directly used in BaseChart.gradientColor2 and DrawArea.gradientColor2. Its contents (in hex) is:
00 C8C8C8 60 F8F8F8 B0 E0E0E0 100 C8C8C8
See Color Specification on how colors are represented in ChartDirector.
ChartDirector 6.0 (ColdFusion Edition)
ChartDirector.CFChart.silverGradient
Description