This is a fantastic vintage Omega Constellation Manhattan 398.864. 
 
This watch has a case which measures 33mm in diameter excluding the signed Omega crown. For its age, the case is in very nice condition showing some signs of use. It has a dark grey dial which shows some marks from the hands under only certain light. The bezel appears to change between black and dark grey depending on the angle. A beautiful combination. The case back has the Omega observatory logo. 
 
The integrated bracelet with signed fold over clasp is an excellent length with 1 spare link. Again, this is in very good condition for its age. 
 
The quartz movement is working correctly keeping great time. 
 
The watch was originally sold in Italy and comes with its guarantee as well as a re-sale receipt from 1996. The original guarantee isn't dated, but from some online research, this dates to 1983. The watch also has its original box which shows it age.