There’s an open secret in the beauty industry and it’s a guilty one: the industry is racist. And it seems a storm is set to break about this, exactly as it did over the size-zero campaign. You might imagine that, among fashionistas, beauty would be welcome in any form, and the more diverse, the better. But you would be wrong. These days, ethnic beauty is pretty much invisible.

Last month, I took a quick snapshot of what you currently see in fashion magazines. I bought 25kg of glossies in random armfuls from a top newsagent; mainly British and American, but also several from Europe, as well as Japanese and Indian Vogue. All those kilograms added up to literally thousands of pages, and the result was conclusive.

Compared to the vast numbers of white girls in them, there were hardly any ethnic models, and few of those were black.

In all the editorial photoshoots and advertisements combined, there were only 163 ethnic women, and of these only 14 were black.

Admittedly, this sample is far from professional market research, but it is striking enough to be worth considering. The fashion world, on this evidence, has been screening out ethnic beauty.

The issue is reaching an anxious tipping point this month with the emergence of a new black supermodel, Jourdan Dunn, the 17-year-old British girl you see pictured on these pages. She was discovered last year while shopping in Primark, and photographers, stylists and editors believe she could go all the way.

She is remarkable, and particularly so because she is black. Sarah Doukas, head of the Storm modelling agency, to which Jourdan is signed, (and who famously discovered Kate Moss), says: “I’m very excited for her. I feel, if she does have great success, she will have a big effect on the way people look at different kinds of beauty.”

Such is the heat around Dunn and the ethnic issue right now that, in an attempt to stave off accusations of inequality, both Italian and American Vogue have been fighting over her for their covers. Italian Vogue’s entire July issue has been shot with black models (the last time it featured one on its cover was 2002); American Vogue has also shot Dunn for its July edition. Incidentally, the last time British Vogue had a black woman (Naomi Campbell) on the cover was also in 2002. Doukas, who this year celebrates 21 years of Storm, says that when she first started out, there was plenty of diversity — not so now. “It’s ridiculous that we have so little diversity in our idea of beauty,” she says.

In the 1960s and 1970s, ethnic women were much more visible in fashion. That was a time of exuberance and change; the time of the Black Power movement, the mantra “black is beautiful”, Roberta Flack singing Be Real Black for Me. This mood continued into the 1980s, with models such as Iman, Pat Cleveland and the young Campbell splashed everywhere.

Fashionistas will admit that it is now extremely rare to see a black girl on a magazine cover, and that there were almost no ethnic girls at the catwalk shows in Paris, Milan and New York in February. One or two Chinese models made it, but otherwise, the Aryan look dominated.

The question is: why? The standard answer is that it all comes down to money. Beauty is what sells — the magazine, the label, the skincare and the bag. Editors and managers say that, however much they want to use ethnic girls, putting one on the cover of a glossy magazine will depress sales. If ethnic women brought in big profits, nobody in the industry would be in the slightest bit interested in their skin tones or their racial type. Rightly or wrongly, though women from ethnic minorities are considered a bad commercial bet.

As one insider said to me regretfully: “Fashion is aspirational, magazines are aspirational and, to aspire, you need to be able to identify with someone – at least a little. And readers don’t identify with ethnic women. They don’t see them as aspirational.”

So, neither the editors nor the advertisers will take any risks on them. This is particularly true in new markets – marketing aimed at the new mega-rich consumers in China and Russia cannot afford to ignore the fact that those countries are more racist than the west.

I’m sceptical about this view. If the assumption that ethnic beauty is unprofitable is right, you would expect advertisers to be even more reluctant to use ethnic models than magazine editors. Editors can afford to take a few risks, perhaps, as fashion leaders, whereas advertisers are much more reactionary, driven by the pursuit of profit. Yet in my snapshot of April magazines, it was the advertisers who were using more ethnic girls.

In all those kilograms of pages, there were only four black women in editorial fashion shoots, and 10 Asian women, whereas there were 71 black women and 48 Asian in advertisements. Four black women in editorials against 71 in advertisements is a striking contrast. It suggests that, in reality, ethnic beauty has greater commercial value than the fashion mavens assume, and that the market has latched onto it first. As Hilary Riva, chief executive of the British Fashion Council, points out: “It is important that we see aspirational images of all types of women in the media. One of the biggest UK ad campaigns, for M&S, has done just that.” Perhaps the punters are a bit less racist than the pundits.

This is only speculation, but it is hard to find much else about this extremely awkward question. British Vogue refuses point blank to comment, and most people I contacted preferred to talk off the record. One suggestion is that the absence, particularly of black girls with African features, has to do with the tiny minority of people who make the fashion weather: the arbiters of fashion. These are the top casting agents and designers who decide whom to send on photoshoots and the catwalks, and many of them are gay white men. I’m told they really don’t like black women. Again, the question is, why? Or, rather, why not? As ever, if it’s not something to do with money, it is probably something to do with sex.

The ideal of female beauty in the fashion industry today is childlike, almost bordering on paedophilia. With few exceptions, the most sought-after faces have small, childish features, with little noses, little chins, small mouths and big, little-girl foreheads and eyes. They are childishly asexual. The same goes for fashionable bodies. The hottest bodies are almost always immature, lacking in secondary sexual characteristics – no curves, no breasts, no body hair.

Those ethnic girls who fit into this stereotype are almost always the ones who succeed. Whatever their skin colour – and paler is more successful than darker – they actually look like white child-women. Asian girls, with their uncurvy, boyish figures and neat features often fit easily into this mould, but models with pronounced African features – large, full lips, wide noses and different facial proportions, as well as more curves, bigger bottoms and fuller breasts – do not. Their look is far from childishly androgynous, however dewily young the girls may be. It is more maturely sexual, more assertively female. Several people have suggested to me that the gay arbiters of fashion find full-on female sexuality distasteful, which is why they don’t favour this kind of womanly beauty among white girls, either.

This, however, can only be part of the explanation. There is also evidence that ethnic women have been ambivalent about their own kind of look for many years. For decades, women with dark skin the world over have tried to make their skin paler or their hair straighter, sometimes with dangerous chemicals. The model Alek Wek recently told Vogue India that, in her native Sudan, her dark skin is looked down on by lighter-skinned Sudanese. “What is this obsession with pigment?” she asked. Marriage adverts in Indian newspapers unselfconsciously express a preference for fair or wheat-coloured skin in women. Japanese and Chinese women regularly have cosmetic operations to remove the fold of skin above their eyes, so they look more like a “round-eyed” European, and dye their hair blonde. As Doukas said of a photoshoot in Japan recently: “The girls just didn’t look Japanese. It was very sad.” Indeed, in my copy of Japanese Vogue, there was a total absence of Japanese models. “I am black but comely,” says the beautiful woman in the Old Testament’s Song of Songs. Why the “but”?

There are, of course, issues of status and power tied up in all this. Most dark-skinned people have been colonised or overrun by pale-skinned people. Pale, in folk memory, means power and wealth, and this has been deeply internalised. Perhaps this is partly why there is some resistance among black and other ethnic women themselves to dark-skinned beauty, even now; perhaps they themselves find something else more aspirational.

Things may, though be beginning to change. The fuss over Jourdan Dunn and her distinctive black beauty may be a sign of the times, a renewed interest in diverse kinds of beauty. “Globally, I think a huge change is about to happen,” Doukas concludes. “I’m optimistic. I think people will come to feel again that diversity is much more interesting than the rather bland, generic look we’ve seen so much of for so long.”