change the color of the last character in a shape text of excel sheet in VBA

Good morning
I would like to change the color of the last character in a shape text of excel sheet in VBA. The Shape is a button and the character on which to change the color is the check mark which is the last character. I can't figure out how to do it, I'm attaching a screenshot to better understand the situation and I'm adding the Sub code.

Public Sub DisegnaSpunta(ByVal lngRow As Long, ByVal strNomeBottone As String)
     
      Application.ScreenUpdating = False
      Dim strSpunta As String
      Dim rngSpunta As Range
      Dim testoBottone As String
     
      With ActiveSheet
          'Questo range serve solo per disegnare le righe sulla colonna G dove erano prima le spunte
          strSpunta = .Cells(lngRow, "G").Address
          Set rngSpunta = Range(strSpunta)
          
          testoBottone = .Shapes.Range(Array(strNomeBottone)).TextFrame.Characters.Text & " " & ChrW(&H2713)
         .Shapes.Range(Array(strNomeBottone)).TextFrame.Characters.Text = testoBottone
         .Shapes.Range(Array(strNomeBottone)).TextFrame.Characters(Start:=Len(testoBottone) - 1, Length:=1).Font.Color = RGB(255, 0, 0)
         
         CambiaBordiCella strSpunta
      End With
      
    Application.ScreenUpdating = True

End Sub

Thanks

Fabrizio