This portrait is painted in enamel on metal. The advantage of enamel over traditional miniature painting (watercolour painted on vellum or, from about 1700, on ivory) is that it does not fade when exposed to light. The process of painting with enamels is, however, less free than the miniature technique and is fraught with danger. The first colours to be laid on the metal support have to be those needing the highest temperature when firing. More colour is added and the enamel refired, the process ending with the colours needing the lowest temperature. Such labour meant that it was an expensive option.

This enamel is by Jean Petitot, a goldsmith and jeweller. Petitot and his friend, the enameller Jacques Bordier, together developed the art of painting portraits in enamel using a previously unexplored range of colours and subtlety of tone. Petitot introduced the court of Charles I in England to this novel art in the late 1630s. It is likely that he left England before the execution of his patron, Charles I, in 1649. Thereafter he practised in France, painting many portraits of Louis XIV, his children and those connected with his court.

The daughter of Walter Stuart, a physician in the household of Queen Henrietta Maria, Frances Stuart was two years old when Charles I was executed and she joined his widowed queen in exile in France. She returned to the restored court aged sixteen in 1660, a renowned beauty and thoroughly imbued with French taste. Her patronage of the French enamellist Petitot is indicative of this. This portrait, painted presumably in France in 1669 (it is signed and dated and inscribed with the sitter's name), anticipates the renewed interest of the English in the hard, bright, jewel-like technique of enamel painting. Within a decade the fashion for enamels rivalled the native tradition of miniatures painted in watercolour.