The duo tried to entice the pensioner into buying jewellery by placing rings in his hand and putting a chain around his neck in the Ash Grove area of Blackburn before speeding off towards B792 Bathgate Road.
After they made their getaway, the man realised his own gold chain with St Christopher medallion had been taken.
The women, described as Asian and in their late 20s to early 30s, were driving a dark-coloured saloon car and targeted the man at around 12.45pm on Saturday. They are around 5ft 7ins tall, medium build with dark shoulder-length hair and wearing scarves over their heads. The driver is also Asian, in his 40s with a medium build, dark hair and a moustache. He was wearing a light blue shirt.