Two different interior cell color give me the same colorIndex VBA

Question

Why two diffrent cells color give me the same ColorIndex ?

I use this function to get the cell color index:

Function InteriorColor(CellColor As Range)
 Application.Volatile
 InteriorColor = CellColor.Interior.ColorIndex
 End Function

This is what the function return:

Answer 1

ColorIndex is limited to 256 Colors, so a broad range of RGB Colors get converted to the same ColorIndex. Use .Color instead, there you are able to use RGB Colors, which are more precise.

Cells(1,1).Interior.Color = RGB(255,255,255)

Answer 2

ColorIndex covers a very limited set of values for a very limited set of colors.

Consider using Color instead.