Use the photograph as your reference
Skin color changes with lighting, shadows and reflected surroundings. A portrait taken in warm evening light needs a different palette from the same person photographed beside a cool window. Choose the image you intend to stitch and evaluate the forehead, cheeks and deepest shadows separately. A palette name is a starting point, not a claim that one set of threads represents every person.
Start with three tonal roles
Choose a highlight, a midtone and a shadow, then decide whether the chart needs intermediate shades. The midtone should carry much of the face; highlights and shadows define form. A larger chart may need more transitions. For a small chart, too many near-identical colors can create scattered stitches without adding visible structure. Compare a simple palette and a broader one at the same chart size.
Inspect transitions around the face
Look at the nose, eye sockets, chin and hairline. If neighboring shades produce abrupt bands, adjust the palette or the source-image settings and regenerate. Do not judge only the swatch row: colors that look plausible separately can behave differently when placed next to hair, clothing and the background. Preserve enough contrast to distinguish the features.
Use digital matching as a starting point
The curated fair, deep and full portrait palettes can help you compare different ranges. They are not exact matches for real thread under every light. The substitute finder ranks screen-color distance and can restrict suggestions to floss you own, but physically compare a replacement against its neighboring threads before using it in a portrait. A close digital match may still alter the gradient.
Stitch a small test
Before a large portrait, test an area containing a highlight, midtone and shadow on your chosen fabric. View it at the distance you expect the finished piece to be seen. If a transition is too harsh, change that pair rather than adding colors everywhere. Record the final thread numbers alongside your saved chart so you can reproduce the palette consistently.