One of my timeless classics that stays that way due to the simplicity in light.
It is a large Octa from above centre but not extremely high maybe 30º. It is also turned down, and towards the camera. It is quite close , the only way to keep the shadow under the neck. Too many pictures are lit with way too much light on the neck, or half way which is generally worse.You can see this as the light on the charcoal grey background has it’s ritual dark on light , light on dark. Also the light on the close edge of the back of Martha is partially graduated , a sure sign of the light being turned towards the camera. I also use black cinefoil to shade if it is still too bright. Sometimes it’s best to leave the light close and have a hot edge (too much light) and shade that with gobos, cinefoil etc so you maintain that special light graduation which makes the volume interesting.
Next there is a second light , a small strip light called a LightBar 60 with barn doors. It is at camera lens height redirecting some of the light back in the eyes and the upper lip. It was very close to the girl and below pointing up. It is quite visible in the close up screen capture. I usually close the barn doors enough so that it doesn’t kill the under chin shadow, yet lights the lips and eye lides. The upper lip is your area to watch for beauty that it doesn’t become excessively shadowed. Of course this depends on the volume of the girls lips>
Next there is a black poly board to keep the shadow side dark, a 120cm Broncolor LightBar with barn doors and a Rosco Peacock filter on the shadow side. That is about it. simple but extremely effective light for classic painterly beauty.
Post prod: make multiple copies in LightRoom, turn up the red brightness for one virtual copy . This one is the one used to make the skin light. Open in layers in Photoshop , mask out what you don’t want.