Casta paintings literally marked near-white women with a black dot at the temple

Evidence

It is revealing, then, that the mark of blackness in Casta paintings is often metaphorically literalized. Many mixed women whose skin tone is painted as especially white will have a large dark black dot planted at the temple, a visible reminder of the social bruise of blackness even where skin color has been so toned down as seemingly to enable evasiveness of the racial hold. — David Theo Goldberg, The Threat of Race, 1111

Categorization

• QUESTION: How widely documented is this temple-dot convention across actual casta painting collections, and did viewers read it consistently as a blackness marker?
• SEED: Angle for an essay: pictorial one-drop rules — how visual culture literalizes racial belonging on the body in paint long before law codifies it.