Vintage Must De Cartier Tank watch, silver gold plated case on leather strap. The movement is quartz. Crystal is scratch resistant sapphire. Watch case diameter is 28 mm. Dial is special brown colour  with  roman numerals.

Cartier’s collection of “essential” vermeil watches was launched in 1977. It resumes the LC Tank shape with its sapphire cabochon crown.
The essential version of the Tank presented to you is the 1977 version: Tank LC vermeil case, dial without numbers, tortoiseshell lacquer.