You might expect an uber-elegant Polish countess, who also happens to be the co-founder of the $715 million beauty brand Sisley, to be a fan of minimalism — but when it comes to her Parisian home, Isabelle d’Ornano, 84, is quite the opposite. “I like a mixture of styles and things that are a bit extravagant. I love color,” says the beauty industry mogul, who launched the luxury cosmetics brand with her late husband, Hubert, in 1976. She now runs the company with her son Philippe, daughter Christine and granddaughter Daria.

A 17th-century clock anchors a gallery wall, which is covered in an Atelier Braquenié textile.

The family’s spacious four-bedroom, four-bathroom apartment, situated on the scenic Quai d’Orsay along the River Seine on the Left Bank of the city, is filled with the kind of eclectic decor, family heirlooms and old photographs that can only be acquired over decades.

“I’ve had the apartment for nearly 50 years and we loved to collect things,” d’Ornano says. It would be difficult — no, impossible — to find a quiet corner in any of the rooms. Every wall is hung with artwork, every surface occupied with ornaments or books, and along the floor runs a handmade multicolored carpet by Braquenié. “When we moved in, all the floors were marble and I thought, ‘I can’t live with marble floors,’ so we put in the wall-to-wall carpet, which has all the other colors of the room in it. Somehow everything mixes well.”

D’Ornano in her element.

Some would assume that owning a prestigious, multimillion-pound beauty business would lead to exclusively expensive taste, but for d’Ornano the blend of valuable artworks with homemade decor and treasured photographs is what makes her apartment a home. “Not everything is valuable, it’s a mixture. Money helps you to have beautiful things but it’s not money that makes a place cozy.”

Take the colorful cushions littered around the living room — d’Ornano hand-stitches these herself, usually while watching television. “I’ve been doing needlepoint since I was about 25. I put words like ‘Love’ or ‘Grace’ on my cushions — I’ve learnt that from contemporary art. A lot of great artists use words because they have a meaning, they signify something.”

No surface is left unadorned.

Carefully placed lighting is another trick d’Ornano uses to help give the apartment its lived-in feel. “Lighting is very important. It should always be on at least three levels.” The first is lamps — some of her favorites include the ones in her bedroom, made by the Paris-based designer Maria Pergay, who is known for her use of stainless steel — “and the lampshades are hand-painted by Maya, a Serbian artist”. D’Ornano recommends always placing lights above pictures hanging on the wall, and the third level is the light from your ceiling, which in this case means grandiose 18th-century crystal chandeliers. For an added touch, d’Ornano says to “always place a light by the places you want to sit — it makes it extra cozy”.

The d’Ornanos were known for hosting informal dinner parties during couture week.

D’Ornano refers to the dining room as the family’s “cozy area”, but it was once famous for their “not very French” informal dinner parties during Paris couture week, where “all kinds of remarkable people, from actors and artists to just our friends” would sit and eat around the table. “The French president [Valéry Giscard d’Estaing] came to one of our parties. It was a very relaxed way of entertaining,” she says. These days things are a bit quieter. “Now I enjoy just having a few friends over for lunch.”

“Money helps you to have beautiful things but it’s not money that makes a place cozy.”

Less low-key, however, is d’Ornano’s love of art, which fills nearly every inch of the apartment — even the ceilings. In the living room, look up and you’ll see a bright blue sky painted with clouds, reminiscent of Renaissance art. D’Ornano puts her love of ceilings down to her Polish heritage — “My family had a beautiful house in Poland, which is where I first saw the idea of ceiling decoration. Ceilings can be great inspiration, especially if you have high walls.”

Museum-quality art and collectible curios are juxtaposed against handmade objects and personal photographs.

In the living room, Anselm Kiefer’s Maria descendant le 3ème jour (The Descent of Mary on the Third Day) sits proudly above the sofa — the countess bought the piece at Sotheby’s shortly after her husband died — while a pair of resin snails by Jean-François Fourtou climb the wall, heading towards the ceiling, alongside giant glass raindrops by the American artist Rob Wynne that run down the window.

Supporting artists is something the countess is passionate about. She began collecting contemporary art 20 years ago, visiting galleries and commissioning designers with ideas for sculptures, such as the antler ornaments on the mantelpiece by a Polish sculptor she discovered in London. Art is the area where d’Ornano is most likely to splurge — “We are lucky, our business is doing well so we can buy art, which is more and more valuable” — but that doesn’t mean she’s any less selective. She is quick to point out there’s a difference between admiring something in a gallery and purchasing it for her own space. “I wouldn’t buy something for my own house just because I like it in someone else’s.” She is also a fan of antiques shops, taking full advantage of the nearby Rue Jacob, a hotspot for vintage pieces in Paris where she found the living room’s black velvet armchairs.

The walls are crawling with snails by artist Jean-François Fourtou.

She is aware that people find her design taste unexpected — when she and her husband moved into the apartment there was so much talk about its style that a whole television program was dedicated to it. While she isn’t opposed to more modern, simplistic-looking rooms, d’Ornano finds them “very much architect rooms — you can’t move anything or it will disturb the whole look”. She prefers the lived-in, familial approach. “As much as our interior is very grand, we brought up five children in this house. They would sit on the floor watching television in the living room or eating around the table in the dining room. There was always some kind of mess around — I like a certain degree of disorder.”

Roisin Kelly is a staff writer at The Sunday Times Style