Excel.Workbook excelWorkbook = excelApp.Workbooks.Open("excel.exls", 0, true, 5, "", "", true, Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
Excel.Worksheet excelWorksheet = (Excel.Worksheet)excelWorkbook.Sheets[1];
Excel.Range excelRange = excelWorksheet.UsedRange;
rowCount = excelRange.Rows.Count;
for (int i = 6; i <= rowCount; i++)
{
  Excel.Range range1 = (excelWorksheet.Cells[i, 1] as Excel.Range);
  if (range1.Value != null)
  {
     string cellValue1 = range1.Value.ToString();
     double? iColorX = excelWorksheet.Cells[i, 1].Interior.Color;
  }
}

Excel.Range range2 = (excelWorksheet.Cells[i, 2] as Excel.Range);