Must de Cartier watch

Must de Cartier watch . Unsure if this is real or not. The stones are in a very good setting (secure) . The watch has some weight . Markings on the back and a number I can't find listed . Bought a bag of watches , years ago , stashed it in a drawer in the basement and just found them again . Several watches marked 17 and 15 jewel but haven't researched them yet . This one is intriguing . However the old saying If it seems too good to be true.......
The writing on the back where it says Swiss is not lined up with the other writing kind of offset. I actually called Cartier in the USA and they were absolutely no help. I was told if someone like a jeweler opens the back the watch is devalued. How can I tell if it is real ?