Worksheet worksheet = workbook.Worksheets[0];

// Set each particular border for the cell.
Cell cellB2 = worksheet.Cells["B2"];
Borders cellB2Borders = cellB2.Borders;
cellB2Borders.LeftBorder.LineStyle = BorderLineStyle.MediumDashDot;
cellB2Borders.LeftBorder.Color = Color.Pink;
cellB2Borders.TopBorder.LineStyle = BorderLineStyle.MediumDashDotDot;
cellB2Borders.TopBorder.Color = Color.HotPink;
cellB2Borders.RightBorder.LineStyle = BorderLineStyle.MediumDashed;
cellB2Borders.RightBorder.Color = Color.DeepPink;
cellB2Borders.BottomBorder.LineStyle = BorderLineStyle.Medium;
cellB2Borders.BottomBorder.Color = Color.Red;

// Set all borders for cells.
Cell cellC4 = worksheet.Cells["C4"];
cellC4.Borders.SetAllBorders(Color.Orange, BorderLineStyle.MediumDashed);
Cell cellD6 = worksheet.Cells["D6"];
cellD6.Borders.SetOutsideBorders(Color.Gold, BorderLineStyle.Double);
// Set all borders for the range of cells in one step.
CellRange range1 = worksheet.Range["B8:F13"];
range1.Borders.SetAllBorders(Color.Green, BorderLineStyle.Double);

// Set all inside and outside borders separately for the range of cells.
CellRange range2 = worksheet.Range["C15:F18"];
range2.SetInsideBorders(Color.SkyBlue, BorderLineStyle.MediumDashed);
range2.Borders.SetOutsideBorders(Color.DeepSkyBlue, BorderLineStyle.Medium);

// Set all horizontal and vertical borders separately for the range of cells.
CellRange range3 = worksheet.Range["D21:F23"];
Formatting range3Formatting = range3.BeginUpdateFormatting();
Borders range3Borders = range3Formatting.Borders;
range3Borders.InsideHorizontalBorders.LineStyle = BorderLineStyle.MediumDashDot;
range3Borders.InsideHorizontalBorders.Color = Color.DarkBlue;
range3Borders.InsideVerticalBorders.LineStyle = BorderLineStyle.MediumDashDotDot;
range3Borders.InsideVerticalBorders.Color = Color.Blue;
range3.EndUpdateFormatting(range3Formatting);

// Set each particular border for the range of cell. 
CellRange range4 = worksheet.Range["E25:F26"];
Formatting range4Formatting = range4.BeginUpdateFormatting();
Borders range4Borders = range4Formatting.Borders;
range4Borders.SetOutsideBorders(Color.Black, BorderLineStyle.Thick);
range4Borders.LeftBorder.Color = Color.Violet;
range4Borders.TopBorder.Color = Color.Violet;
range4Borders.RightBorder.Color = Color.DarkViolet;
range4Borders.BottomBorder.Color = Color.DarkViolet;
range4.EndUpdateFormatting(range4Formatting);

Dim worksheet As Worksheet = workbook.Worksheets(0)

' Set each particular border for the cell.
Dim cellB2 As Cell = worksheet.Cells("B2")
Dim cellB2Borders As Borders = cellB2.Borders
cellB2Borders.LeftBorder.LineStyle = BorderLineStyle.MediumDashDot
cellB2Borders.LeftBorder.Color = Color.Pink
cellB2Borders.TopBorder.LineStyle = BorderLineStyle.MediumDashDotDot
cellB2Borders.TopBorder.Color = Color.HotPink
cellB2Borders.RightBorder.LineStyle = BorderLineStyle.MediumDashed
cellB2Borders.RightBorder.Color = Color.DeepPink
cellB2Borders.BottomBorder.LineStyle = BorderLineStyle.Medium
cellB2Borders.BottomBorder.Color = Color.Red

' Set all borders for cells.
Dim cellC4 As Cell = worksheet.Cells("C4")
cellC4.Borders.SetAllBorders(Color.Orange, BorderLineStyle.MediumDashed)
Dim cellD6 As Cell = worksheet.Cells("D6")
cellD6.Borders.SetOutsideBorders(Color.Gold, BorderLineStyle.Double)
' Set all borders for the range of cells in one step.
Dim range1 As CellRange = worksheet.Range("B8:F13")
range1.Borders.SetAllBorders(Color.Green, BorderLineStyle.Double)

' Set all inside and outside borders separately for the range of cells.
Dim range2 As CellRange = worksheet.Range("C15:F18")
range2.SetInsideBorders(Color.SkyBlue, BorderLineStyle.MediumDashed)
range2.Borders.SetOutsideBorders(Color.DeepSkyBlue, BorderLineStyle.Medium)

' Set all horizontal and vertical borders separately for the range of cells.
Dim range3 As CellRange = worksheet.Range("D21:F23")
Dim range3Formatting As Formatting = range3.BeginUpdateFormatting()
Dim range3Borders As Borders = range3Formatting.Borders
range3Borders.InsideHorizontalBorders.LineStyle = BorderLineStyle.MediumDashDot
range3Borders.InsideHorizontalBorders.Color = Color.DarkBlue
range3Borders.InsideVerticalBorders.LineStyle = BorderLineStyle.MediumDashDotDot
range3Borders.InsideVerticalBorders.Color = Color.Blue
range3.EndUpdateFormatting(range3Formatting)

' Set each particular border for the range of cell. 
Dim range4 As CellRange = worksheet.Range("E25:F26")
Dim range4Formatting As Formatting = range4.BeginUpdateFormatting()
Dim range4Borders As Borders = range4Formatting.Borders
range4Borders.SetOutsideBorders(Color.Black, BorderLineStyle.Thick)
range4Borders.LeftBorder.Color = Color.Violet
range4Borders.TopBorder.Color = Color.Violet
range4Borders.RightBorder.Color = Color.DarkViolet
range4Borders.BottomBorder.Color = Color.DarkViolet
range4.EndUpdateFormatting(range4Formatting)