1951 Longines classic Sei Tacche Watch with Mixed Arrow and Arabic Numerals Model 5697This Watch We have here a stunningly aged longines Sei Tacche Reference 5697 (6 case back notches) The dial has the most unusual and in our opinion fantastic patina, almost like a baked caramel ,pumpkin soup effect or indeed Crme brle This gives no doubt to its originality. This patina is usually caused by a hot humid environment but we have also seen this effect happen to vintage window stock where the shop front window acts as a magnifying glass