In men and women of a certain age, the absence of any grey hair can lead to cynical suggestions that they have been reaching for a bottle of dye.
But a study indicates those accusations could be groundless -- at least for a lucky few.
Researchers have discovered that one in 10 of the over-60s does not have any grey hair, which could mean the cloud of suspicion can be lifted from those who -- like Selina Scott, 61, the broadcaster, and actresses Cherie Lunghi, 60, Susan Sarandon, 65, and Sigourney Weaver, 62 -- seem, against all the odds, to have clung on to the colour of their younger days.
The worldwide study found that the prevalence of grey hair in men and women was less than previously thought.
The survey, which is published in the British Journal of Dermatology, was conducted by the research and development arm of the cosmetics manufacturer L'Oreal.
The research involved analysis of the natural hair colour of more than 4,000 men and women, from a range of ages and ethnic backgrounds, from more than 20 countries. Overall, of those aged between 45 and 65, 74 per cent had some grey hair.
Among those aged between 45 and 50, 63 per cent had some grey hair.
This rose to 78 per cent of people aged between 51 and 55, with an average of 26 per cent of their hair being grey.
In 56 to 60-year-olds, 86 per cent had some grey -- over an average of almost a third of their hair.
In the final category, 61 to 65-year-olds, 91 per cent had grey hair, over an average of 40 per cent of their head.
Grey hair was more common in men (78 per cent), than women (71 per cent).