conditionnement, ou formule 2 couleurs 1 cellule

Option Explicit

Public Sub Test()
Concat Cel0:=Range("B2"), Cel1:=Range("A1"), Cel2:=Range("C1")
End Sub

Sub Concat(Cel0 As Range, Cel1 As Range, Cel2 As Range)
    Cel0 = Cel1.Text & Cel2.Text
    With Cel0.Characters(Start:=1, Length:=Len(Cel1.Text)).Font
        .Name = Cel1.Font.Name
        .FontStyle = Cel1.Font.FontStyle
        .Size = Cel1.Font.Size
        .Strikethrough = Cel1.Font.Strikethrough
        .Superscript = Cel1.Font.Superscript
        .Subscript = Cel1.Font.Subscript
        .OutlineFont = Cel1.Font.OutlineFont
        .Shadow = Cel1.Font.Shadow
        .Underline = Cel1.Font.Underline
        .ColorIndex = Cel1.Font.ColorIndex
    End With
    With Cel0.Characters(Start:=Len(Cel1.Text) + 1, _
            Length:=Len(Cel1.Text) + Len(Cel1.Text)).Font
        .Name = Cel2.Font.Name
        .FontStyle = Cel2.Font.FontStyle
        .Size = Cel2.Font.Size
        .Strikethrough = Cel2.Font.Strikethrough
        .Superscript = Cel2.Font.Superscript
        .Subscript = Cel2.Font.Subscript
        .OutlineFont = Cel2.Font.OutlineFont
        .Shadow = Cel2.Font.Shadow
        .Underline = Cel2.Font.Underline
        .ColorIndex = Cel2.Font.ColorIndex
    End With
End Sub