ColorIndex in Excel VBA
Today let’s try to understand how ColorIndex property in Excel VBA works. It is an easy and effective way to quickly complete the development. ColorIndex property is normally used by VBA developers to fill cell, border and font colors. ColorIndex returns values from 1 to 56, -4105 and -4142.
From index 1 to 56 are actual colors which provides various types of colors. Have a look at below color variations

Let us now see how we can implement ColorIndex in VBA codes:
Example 1: Changing Cell Color

Code:
Sub ColorIndexExample1()
Sheet1.Range("C2").Interior.ColorIndex = 1 'Black
Sheet1.Range("C3").Interior.ColorIndex = 3 'Red
Sheet1.Range("C4").Interior.ColorIndex = 5 'Blue
End Sub
Explanation:
Here we have set the color of the cell using ColorIndex. ColorIndex = 1 is used to change the cell color to Black. Similarly, ColorIndex 2 and 3 are used to change the cell color to Red and Blue respectively.
Example 2: Changing Border Color

Code:
Sub ColorIndexExample2()
Sheet1.Range("C2").Borders.ColorIndex = 3 'Red
Sheet1.Range("C3").Borders.ColorIndex = 4 'Green
Sheet1.Range("C4").Borders.ColorIndex = 6 'Yellow
End Sub
Explanation:
In the above code, we have changed the border color of the cells using ColorIndex property available under Borders function of Range.
Example 3: Changing Font Color

Code:
Sub ColorIndexExample3()
Sheet1.Range("B2").Font.ColorIndex = 1 'Black
Sheet1.Range("B3").Font.ColorIndex = 3 'Red
Sheet1.Range("B4").Font.ColorIndex = 5 'Blue
End Sub
Explanation:
In this third example, we have changed font color of the cell using ColorIndex property.
How -4105 (xlColorIndexAutomatic) and -4142 (xlColorIndexNone) Works
Both -4105 and -4142 are special enumeration to set the ColorIndex to Automatic or None. If ColorIndex is supplied as -4105 (xlColorIndexAutomatic) then cell color, border or font is set to Automatic. Below is a sample code

Code:
Sub ColorIndexExample4()
Sheet1.Range("C2").Interior.ColorIndex = xlColorIndexAutomatic
End Sub
Explanation:
The above code changes the cell color of C2 on Sheet1 to Automatic which is white here.
Similarly, -4142 (xlColorIndexNone) is used to set ColorIndex to none. Below is a sample code of the same:

Code:
Sub ColorIndexExample5()
Sheet1.Range("C3").Interior.ColorIndex = xlColorIndexNone
End Sub
Explanation:
The above code changes the cell color of C3 on Sheet1 to None.
How to Get ColorIndex of a Cell?
Below is sample code to get the ColorIndex value of a Cell Color, Font or Border:

Code:
Sub ColorIndexExample6()
Sheet1.Range("C2").Value = Sheet1.Range("B2").Interior.ColorIndex 'Cell ColorIndex
Sheet1.Range("C3").Value = Sheet1.Range("B3").Font.ColorIndex 'Font ColorIndex
Sheet1.Range("C4").Value = Sheet1.Range("B4").Borders.ColorIndex 'Border ColorIndex
End Sub
Explanation:
In the above code, we are reading ColorIndex of Cell, Font and Border Colors the value of ColorIndex is then stored back in the sheet in column C.
Excel VBA Color Constants
You can also make use of few color Constants defined in Excel VBA for quick reference.

Code:
Sub ColorConstantsExample()
Sheet1.Range("C2").Interior.Color = vbBlack
Sheet1.Range("C3").Interior.Color = vbBlue
Sheet1.Range("C4").Interior.Color = vbCyan
Sheet1.Range("C5").Interior.Color = vbGreen
Sheet1.Range("C6").Interior.Color = vbMagenta
Sheet1.Range("C7").Interior.Color = vbRed
Sheet1.Range("C8").Interior.Color = vbWhite
Sheet1.Range("C9").Interior.Color = vbYellow
End Sub
There is also one more way to work with colors using RGB (Red Green Blue) function. The function requires 3 numbers from 0 to 255 [e.g. RGB(23,122,98)]. Have a look at below code:

Sub RGBExample()
Sheet1.Range("B2").Interior.Color = RGB(255, 0, 0) 'Red
Sheet1.Range("B3").Interior.Color = RGB(0, 255, 0) 'Green
Sheet1.Range("B4").Interior.Color = RGB(0, 0, 255) 'Blue
End Sub
Explanation:
In the above code, we are using RGB VBA function to change the cell colors.
Have a look at How to ger RGB Codes of a Color and VBA Code to Change Cell Color post to know more about this.