Participants preferred the women to display a reddish hue (right)
Women may be onto something when they reach for the blusher - people really do think healthy females should display a rosy glow, a study suggests.
A team at the University of St Andrews asked a series of volunteers to digitally enhance photographs of men and women to make them look healthy.
The results, published in the journal PLoS One, found all participants added more red to the skin of their subjects.
But the female faces received more colour than their male counterparts.
In particular, participants added more of the hue given by bright red oxygenated blood to the female faces - regardless of the ethnicity of either the volunteer or the subject.
This colouring was given preference over slightly bluer deoxygenated blood, which is travelling back to the heart. Those who are physically well tend to have more oxygenated blood.
Although the difference between the colours of the two sorts of blood is subtle, researchers said they were surprised at the participants' ability to register it.
There was no difference between male and female participants in the colour they gave to the faces.
"But that does not mean there isn't a sexual basis to this," said lead researcher Ian Stephen of the University of St Andrews.
"Women are perfectly capable of judging the attractiveness of other women, and from an evolutionary perspective need to do so if they are to effectively assess the competition."
As well as being reflective of general fitness, redness in women is associated with increased levels of the sex hormone oestrogen.
The researchers recommended you increase your levels of exercise or give up smoking as one way of boosting your rosy hue, and thus your level of attractiveness.
But women have been cheating on this front for years.
The Egyptians are known to have coloured their cheeks with a variety of substances including a red clay while the Elizabethans used a form of mercury to give themselves a rouge tint.
But the team also found that you can have too much of a good thing. A very red face was not deemed to be healthy, perhaps because of its association with alcoholism and other ailments, the researchers speculated.
George Fieldman, a London-based cognitive behavioural therapist said colour was likely to be key in any decision to pick a mate.
"If you are looking for long-term partner you want to get some indication of whether they are likely to stick around," he said.
"And even if you are after a more short-term relationship, facial hue could provide insight into the likelihood of picking up a disease."
Ben Jones, head of the Face Research Laboratory at Aberdeen University, said it was interesting that the findings were the same regardless of ethnicity.
"This suggests that preferences for a healthy glow are not bound by culture - in fact these preferences appear to transcend culture, suggesting that they have a biological basis."