Cameos featuring detailed profiles of Black men and women in precious
metals and jewels were popular in many European countries. The ones
above date circa 1500-1800. Some art historians relate the style above
to the Black King Balthazar or certain saints, others invoke the
association of Blackness with wealth that came though trade in the Middle Ages and Renaissance.
You can read more about cameos like these in Black Africans in Renaissance Europe By K. J. P. Lowe, p. 204-206, and Early Modern Visual Culture: Representation, Race, and Empire in Renaissance England By Peter Erickson & Clark Hulse, p. 193-198.