The fitting room at Jacquemus's Marais atelier runs narrow — three metres wide, maybe four

The fitting room at Jacquemus's Marais atelier runs narrow — three metres wide, maybe four. Simon Porte Jacquemus stands at one end, arms crossed, watching a toile drape over a model's shoulder. At the other end, kneeling with a pincushion strapped to her wrist, is Delphine Roux. She has been with the house since 2014, back when the team fit into a single room in the 10th arrondissement. Today she is première d'atelier for womenswear, which means her hands shape nearly every garment that carries the Jacquemus label.

Roux trained at the École de la Chambre Syndicale, the same programme that fed Dior and Balenciaga their cutters in the postwar decades. She spent five years at Chloé before Jacquemus hired her at twenty-nine. Her specialty, then and now, is draping — building a garment directly on the body rather than drafting it flat. This matters more at Jacquemus than at most houses, because the collection's entire visual grammar depends on a single gesture: the way fabric clings, then releases.

Take the Le Haut Saudade, a halter top introduced in the Spring/Summer 2019 collection and since produced in sixteen iterations. The piece looks simple in photographs — a triangle of jersey, a knot at the nape, an open back. In three dimensions it is a feat of engineering. The fabric must sit flush against the sternum without gaping, which requires the grain line to run on a bias. The knot must hold its shape after six hours of wear, which means the ends are internally weighted with a strip of grosgrain. And the whole construction must survive a 30-degree wash cycle, which Roux tests personally before approving any new colourway.

She is not the only hand in the process. The Saudade top begins with a drape by Roux, then moves to the modéliste Anaïs Leclerc, who translates the three-dimensional form into a flat pattern. Leclerc has worked at Jacquemus since 2016. She came from Courrèges, where she spent four years learning to work with technical knits — the kind that hold their shape under tension. At Jacquemus, her role is to make Roux's drapes reproducible. A single toile might go back and forth between them seven or eight times before it is approved for sampling.

Once the pattern is finalised, it goes to the atelier de coupe, where Karim Benali cuts the fabric. Benali is fifty-three, trained at a small tailoring house in the Sentier, and joined Jacquemus in 2018. He works with a straight knife, not a rotary cutter, because the Saudade top requires cuts on the bias and a rotary blade can stretch the grain. Each piece is cut individually, even in production runs of three hundred units. This is unusual for a contemporary brand at Jacquemus's price point — the top retails at €290 — but it is the only way to maintain the fit that Roux and Leclerc have calibrated.

The garment then moves to the machinistes, a rotating team of five sewers who work on Juki industrials in a separate room. The lead machinist for knitwear is Fatima El Amrani, who has been with the house since 2015. She came from a lingerie atelier in Pantin, where she learned to handle stretch fabrics without distorting their recovery. At Jacquemus, she oversees the topstitching on all jersey pieces, which must be executed at a specific tension — too tight and the fabric puckers, too loose and the seam ripples after washing.

El Amrani's work is invisible in the finished garment, which is precisely the point. The Saudade top has four seams: two at the side, one at the centre back, and one at the neckline. Each seam is topstitched in a matching thread, using a stitch length of 2.5 millimetres. The thread is a polyester-cotton blend, chosen because it has the same stretch coefficient as the jersey itself. This detail was not part of the original specification. It emerged after the first production run in 2019, when several customers reported that the neckline seam had snapped. El Amrani identified the problem — the thread was 100 per cent cotton, which has no give — and sourced a replacement.

The house does not advertise these details. Jacquemus's public image is built on sun-drenched campaigns and oversized accessories, not atelier process. But the work is there, layered into every piece that leaves the Marais studio. Roux estimates that she and her team produce between forty and fifty toiles per collection, each one tested on a fit model and adjusted until it meets the house's standard. The standard, she says, is simple: the garment must look unconstructed, but it must not move once it is on the body.

This is harder than it sounds. Contemporary fashion tends toward two extremes — either rigidly tailored or deliberately loose. Jacquemus operates in the margin between them, which requires a level of precision that is difficult to scale. The Saudade top, for instance, cannot be graded using a standard sizing algorithm. Each size requires its own drape, because the relationship between bust circumference and back length changes as the body gets larger. This means Roux must drape six separate toiles for a single style, each one adjusted to fit a different frame.

She does this work without complaint, but she is not sentimental about it. When asked about her role in the house's success, she demurs. "I make the clothes fit," she says. "Simon makes them matter."

This division of labour is typical in fashion, where the designer's name appears on the label and the artisan's name appears nowhere. But it is also a simplification. Jacquemus's vision — the idea of a garment that feels effortless but looks considered — cannot exist without Roux's draping, Leclerc's patterns, Benali's cuts, and El Amrani's seams. The vision is collaborative, even if the credit is not.

The house is now preparing for its tenth anniversary, which will be marked with a retrospective at the Musée des Arts Décoratifs in 2025. Roux and her team have been asked to recreate several early pieces for the exhibition, including a draped dress from the Spring/Summer 2013 collection that no longer exists in the archive. The original was made in a cotton voile that is no longer produced, so Leclerc is sourcing a substitute with a similar hand. Benali will cut the fabric using the same technique he used in 2018, even though the dress predates his tenure. El Amrani will execute the seams, matching the stitch length to the original even though no technical specifications survive.

This is the work that sustains a fashion house — not the runway, not the campaign, but the accumulated knowledge of the atelier. Roux has been at Jacquemus for a decade now, long enough to train two assistants who have since moved on to other houses. Leclerc is in her eighth year. Benali is in his sixth. El Amrani is in her ninth. They are not household names, and they likely never will be. But they are the reason a Jacquemus garment fits the way it does, and that is not a small thing.