‘Mr Marino doesn’t know what’s coming,’ says Martine Goossens of the staircase design she is creating for Chanel’s new London watch and jewellery boutique. Designed by Peter Marino, the three-storey emporium, due to open in early November, marks a significantly expanded presence for Chanel’s watch and jewellery business. ‘It is my creation but he knows my work, so he leaves it up to me,’ she says of her collaborative process with Marino, a master of luxury retail design.

In making the balustrade entirely by hand, Martine, of Paris’ jewellery house Goossens, is carrying on a family tradition of creating what she terms ‘bijoux espace’ – ‘jewels for the home’ – a creative strand that grew from her father Robert’s jewellery design work with Coco Chanel. The fashion house subsequently acquired the Goossens studio in 2005, but Marino has been incorporating its baroque jewelled creations into his interiors for Chanel since the mid-1990s. Having looked at the architectural drawings for the London store, Martine sketched out the form of the balustrade in blue and red ballpoint. The gilt-bronze panels were created using the ancient lost-wax method, where a plaster mould is made from a wax cast of the design; hot metal is then poured in after the wax has melted away.

‘The bronze is strong and voluptuous, so I had to create the juxtaposition of light,’ she explains. ‘Rock crystal has a magical, dreamlike quality – everyone sees something different when they look at it.’ The rock-crystal cabochon studs connecting the panels were designed to be tactile, in the way the best jewellery designs are. ‘I had this idea of making it seem as though you are looking at them through a loupe, so they become magnified. You look at them and want to touch them.’

Martine also adhered to the tradition of a designer leaving their mark on a commission, humorously making the cabochons 5 sq cm, in a nod to Chanel No 5. ‘Well, it is Chanel. It’s extraordinary to work on this.’