At times, Bucar explains, their style is intentionally political and subversive. At others, it is aimed purely at modesty – as the faith dictates. And sometimes, it is all about fashion, beauty and personal delight.

But Bucar, an associate professor of philosophy and religion at Northeastern University in Boston, balances her academic inquiry with the wide-eyed surprise of an eager fashion student. She boils down generations of political change into a few easily digestible paragraphs.

Historians might be horrified, but this isn’t a book about revolution in Iran or colonialism in Indonesia. It isn’t even about the traditions of batik fabric or styles of dress in the Ottoman Empire, although there is a bit of that here. Pious Fashion is a look at contemporary dress and how it can help us see the “Muslim community” as a vast array of individuals, rather than an inscrutable monolith.

Bucar argues that fashion is a form of communication and self-identity. Some readers will find that position alone provocative. Using “pious fashion”as a tool for exploring diversity among Muslim women will undoubtedly be seen as both subversive and political by many. But Bucar strives to be non-judgmental and apolitical.

As part of her research, she organised focus groups, visited college campuses, interrogated shopkeepers and loitered in bustling neighbourhoods like an itinerant street-style photographer. It should not take that much effort just to document what should be so obvious to non-Muslims. But this is where we are in 2017: overwhelmed by assumptions, prejudices, ignorance and miscommunication.

Bucar tells her readers up front that she is not a fashion expert. When readers first meet her, it is 2004 and she is flying to Tehran to study Persian. In advance of her trip, she has been struggling with her attire, attempting to figure out how best to abide by local laws dictating that women wear proper hijab. This is more challenging than she expects because “hijab” is not a uniform or a specific dress code. It simply means modest dress, and that is open to interpretation depending on occasion, geography, social class and a host of other elements.

It is not as simple as covering herself from head to toe in black wool because, under the wrong circumstances, that would be akin to a man showing up for a business meeting in Silicon Valley wearing a top hat and morning coat. It would be overly formal, terribly self-conscious and a bit ridiculous.

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There are nuances of pious fashion that are rooted in history and politics. Those nuances change from country to country, as do the terms used to describe modest attire. Bucar focuses her attention mostly on 20-something women because they were most accessible to her and because, she believes, they are most attuned to and interested in fashion. She speaks to groups of them in Tehran, where hijab is dictated by law.

She visits Yogyakarta in Indonesia, where pious dress is a choice. There, it is generally seen as the culmination of a personal journey of self-awareness and self-improvement. It is a style of dress, but it is also a personal commitment.

In Istanbul, Bucar learns that women’s clothing styles are a reflection of the tensions within Turkey itself: its European-ness, its secularism, its Islamic character. Here, too, a head covering is a matter of choice.

For those women who decide to cover their heads, the choice of scarf is significant. Women experiment to find the most flattering colour and the most attractive way of securing it around their heads. Perhaps they wear a little faux bun under the scarf to create the illusion of an abundance of (hidden) hair and to elongate their faces. They consider how the scarf will accent the rest of their attire. In Istanbul they will often fold the scarf in such a way that the identifying brand tag hangs off the back for all to see.

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In Iran, pious fashion means not showing the curves of the body. In Indonesia, it means covering the body, but an hourglass figure is celebrated. There is no tension between being modest and being attractive. In Turkey, dressing modestly carries a particular onus to be beautiful and stylish as well, lest a woman look old-fashioned and out of touch in a country that strives to look forward.

While Tehran has its hijab enforcers, what’s appropriately pious is something that seems to be forever in flux. It is not simply a question of whether a woman should or should not show her hair or her ankles, but also a matter of how she chooses to cover herself. Is it too ostentatious? Too matronly? Too matchy-matchy? The answer is influenced by cultural norms that are, in part, dictated by other women, local fashion designers and even fashion bloggers. Instagram, it seems, knows no bounds.

Bucar disabuses readers of any preconceived ideas that women who adhere to an aesthetic of modesty are unfashionable or frumpy. They are far from it. Indeed, a photograph of a woman in Turkey wearing an ankle-length leather dress (fitted through the bodice and with a flared skirt) paired with a lace scarf and a structured handbag exudes sophistication and elegance. What she wears and how she wears it are her choice, and she has chosen skilfully.

The source of some of Bucar’s most striking images of women in Tehran is a fashion blog called The Tehran Times, founded by an Iranian fashion designer named Araz Fazaeli. The blog includes photographs of art as well as pictures of women snapped on the street – women who are dressed in ways that would delight any social-media addict.

“The main issue in Iran is not the dress code,” Fazaeli says. “Fashion is creative enough to make its way through any restrictions.”

This is true. Fashion always finds a way.

But the question that keeps nagging is this: why should there be any restrictions to begin with? Why should a government create laws that impinge on a woman’s right to choose her attire freely? Bucar says that when a culture invests so much of its identity in the appearance and piousness of women, it is also investing women with a cultural and social power. Perhaps. It is an interesting argument but not one that Bucar makes convincingly.

Still, she introduces her readers to the lively Muslim women in her focus groups. They are thoughtful and stylish, funny, opinionated, devout, and delightfully bitchy when they are asked to assess the style chops of their peers and some of the local fashion editors.

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In the conversations Bucar has with them, we learn that they, like women who call themselves Methodist, Catholic, Jewish or atheist, are simply trying to present their best selves to the public. And no matter who you are or where you live, that can be complicated.