With your skin tone selected, enable Gamut Lock → Analogous . Move your brush to paint shadows. The gamut lock forces the shadows to be a cooler, darker neighbor hue (e.g., purple-brown) instead of desaturated black.
Pick an orange-brown from the triangle. Drag the Hue ring slightly toward yellow. Notice how the triangle’s vertical axis controls brightness—keep the skin in the upper 40% to avoid chalkiness. Coolorus 2.5.14
Official Coolorus website (trial available) or Adobe Exchange. Note: Version 2.5.14 is the last release to support Photoshop’s UXP framework fully. Future versions may require Creative Cloud 2024+. If you are on an older CC version (2018–2022), stick with 2.5.14. With your skin tone selected, enable Gamut Lock