Colorizing a portrait from a color reference

A grayscale portrait of a woman in a dark lapelled coat, with an unverified plain backdrop.

BeforeAfter

Keep the facial identity.
Use approximate skin color direction.
Blend the color boundary.
Follow the blue coat direction.
Mark estimated color.
Keep the scan texture.
Retain the original shadows.
Retain source lightness.

Complete color reference, different chosen pose

Complete color portrait with chin resting on the hand; a different pose from the black-and-white main

The blue coat, skin and hair suggest the color direction. This is the full reference, not a restricted crop. It does not prove absolute historical colors or physical garment identity. The selected main has an unobstructed cheek and a hand on the armrest.