Marguerite of Angouleme (1492-1549) was the sister of King Francis I of France. Two years after her first husband's death in 1525, she married Henry of Navarre and became queen of the tiny kingdom of Navarre.  She is portrayed here as a widow, contemplating a cross; on the reverse is an image of the Virgin with her mother and family known as the Holy Kinship, perhaps to honor the queen's own family.  In the 1600s, she remained highly regarded for her writings, chiefly on the challenge of reconciling a worldly life with a Christian one.
The subtle execution would be remarkable for an enamel portrait of 1525-27, and is more consistent with later portraits by Leonard Limosin, who worked for Marguerite's husband Henry.  The effect of the white bust against a dark oval background is like a Roman cameo.  There are at least three versions of this fine portrait, probably made for relatives and admirers.
<bdi><a href="https://en.wikipedia.org/wiki/en:L%C3%A9onard_Limousin" class="extiw" title="w:en:Léonard Limousin"><span title="French painter and engraver (c.1505-c.1575)">Léonard Limousin</span></a>
</bdi>
between circa 1540 and circa 1545 <div style="display: none;">date QS:P571,+1540-00-00T00:00:00Z/8,P1319,+1540-00-00T00:00:00Z/9,P1326,+1545-00-00T00:00:00Z/9,P1480,Q5727902</div>? (<a href="https://en.wikipedia.org/wiki/en:Renaissance" class="extiw" title="w:en:Renaissance"><span title="cultural movement that spanned the period roughly from the 14th to the 17th century">Renaissance</span></a><div style="display: none;">era QS:P2348,Q4692</div>)
<a href="https://en.wikipedia.org/wiki/en:Walters_Art_Museum" class="extiw" title="w:en:Walters Art Museum"><span title="art museum in Baltimore, Maryland, United States">Walters Art Museum</span></a>: <a href="https://thewalters.org/" rel="nofollow"><img alt="Nuvola filesystems folder home.svg" src="https://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Nuvola_filesystems_folder_home.svg/20px-Nuvola_filesystems_folder_home.svg.png" decoding="async" width="20" height="20" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Nuvola_filesystems_folder_home.svg/30px-Nuvola_filesystems_folder_home.svg.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Nuvola_filesystems_folder_home.svg/40px-Nuvola_filesystems_folder_home.svg.png 2x" data-file-width="128" data-file-height="128"></a> <a rel="nofollow" class="external text" href="https://thewalters.org/">Home page</a> <a href="https://art.thewalters.org/detail/28332" rel="nofollow"><img alt="Information icon.svg" src="https://upload.wikimedia.org/wikipedia/commons/thumb/3/35/Information_icon.svg/20px-Information_icon.svg.png" decoding="async" width="20" height="20" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/3/35/Information_icon.svg/30px-Information_icon.svg.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/3/35/Information_icon.svg/40px-Information_icon.svg.png 2x" data-file-width="620" data-file-height="620"></a> <a rel="nofollow" class="external text" href="https://art.thewalters.org/detail/28332">Info about artwork</a>