This example uses the GridLineColor property.
gcSpreadSheet1.Workbook.GridLineColor = Windows.UI.Colors.Green;
gcSpreadSheet1.Workbook.ShowGridLine = true;
gcSpreadSheet1.Workbook.GridLineColor = Windows.UI.Colors.Green
gcSpreadSheet1.Workbook.ShowGridLine = True
Target Platforms: Windows Server 2012, Windows RT