Function SumColor(rColor As Range, rSumRange As Range)
''''''''''''''''''''''''''''''''''''''
'Written by Ozgrid Business Applications
'www.ozgrid.com
'Sums cells based on a specified fill color.
'''''''''''''''''''''''''''''''''''''''
Dim rCell As Range
Dim iCol As Integer
Dim vResult

iCol = rColor.Interior.ColorIndex
For Each rCell In rSumRange
If rCell.Interior.ColorIndex = iCol Then
vResult = WorksheetFunction.Sum(rCell) + vResult
End If
Next rCell
SumColor = vResult
End Function


via 2 Excel Functions/Formulas to Count/Sum Excel Cells by Color – Excel VBA User Defined Functions.

ColorIndex Property
The ColorIndex property can generate up to 57 colors. The table shown in Figure 1 illustrates the range of colors. The table was created programmatically by using a procedure similar to one shown later in the linked article. Figure 1. ColorIndex values and colorsFigure 1 shows the color palette and the corresponding integer value assigned to the ColorIndex property to produce the color. The ColorIndex property can be applied to the following parent objects:Interior ObjectFont ObjectBorder ObjectBorders ObjectFormatColor ObjectTab Object

via Adding Color to Excel 2007 Worksheets by Using the ColorIndex Property.