public CIMPolygonSymbol Symbol {get; set;}

{
    //create marker from the Font, char index,size,color
    //Note: Needs QueuedTask to run
    var cimMarker = SymbolFactory.Instance.ConstructMarker(125, "Wingdings 3", "Regular", 6, ColorFactory.Instance.BlueRGB) as CIMCharacterMarker;
    var polygonMarker = cimMarker.Symbol;
    //modifying the polygon's outline and fill
    //This is the outline
    polygonMarker.SymbolLayers[0] = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.GreenRGB, 2, SimpleLineStyle.Solid);
    //This is the fill
    polygonMarker.SymbolLayers[1] = SymbolFactory.Instance.ConstructSolidFill(ColorFactory.Instance.BlueRGB);
    //create a symbol from the marker 
    //Note this overload of ConstructPointSymbol does not need to be run within QueuedTask.Run.
    var pointSymbol = SymbolFactory.Instance.ConstructPointSymbol(cimMarker);
}