She apprenticed with the Worshipful Company of Spectacle Makers under the Master George Willdey, earning her Freedom by Servitude on January 8, 1735.
In the early 1750s, Passavant opened her own retail shop, The Plume of Feathers, on Ludgate Hill.
She sold a wide range of goods, including accessories, jewelry and toys.
The Plume of Feathers was involved in the sale of luxury goods both domestically and internationally.
Through her association with the London merchant house Robert Cary & Company, she exported the sale of jewelry to American customers, including George Washington and Martha Washington.