Colors

Use Color Index to Apply custom color

Circle circle = new Circle();
circle.ColorIndex = 1;

- Autocad has different color index for each color - red color has index of 1 - if you don't want to remember color index you can use CadColor Enum from cadhelper

Circle circle = new Circle();
circle.ColorIndex = (int)CadColor.Yellow;

USE RGB to specify Color

circle.Color = Autodesk.AutoCAD.Colors.Color.FromRgb(255, 0, 0);

- (255,0,0) represent red color in rgb value