Cartier, a white gold fob watch, mid 20th century

Cartier, a white gold fob watch, mid 20th century, the square white dial with black Roman numeral indicators and blue steel hands, within a plain square case, to a triangular suspension hoop, length 5.2cm including suspension hoop, manual winding movement, dial signed Cartier, movement signed European Clock and Watch Co., interior of case with French assay mark for 18ct gold, maker's mark EJ with hour glass for Jaeger, numbered 10253, 3743 and 4517, case back interior numbered 5253 and 3743, later case stamped Cartier