April Hershberger is not the only collector of Le Creuset cookware who owns so many pieces that she can’t count them. But she may be the only one who built an entire house around one: the deep-red, nine-quart oval Dutch oven that she received as a gift for her 2006 wedding.

It sparked an obsession.

She had her kitchen stove, the centerpiece of her home in a restored barn in southeastern Pennsylvania, custom-made to match her collection of Le Creuset cherry-red pots, baking dishes, pitchers, plates and more. Ms. Hershberger, 42, also has pieces in mustard yellow and sunflower yellow, Mediterranean blue and Caribbean blue, forest green and lime green, which she frequently arranges and rearranges into stripes, swirls and rainbows, documenting it all on Instagram.

“I could never commit to one color,” she said.

Like Hermès and Chanel, Le Creuset (luh cruh-SAY, according to the official video, meaning French for crucible) is a Gallic legacy brand that has flourished in the modern global marketplace by becoming collectible while also remaining functional. And collectors have turned what was once a niche brand into a near-cult, perpetually entranced by new lines, colors and shapes.

Some stick to a color family, like pastels; others focus on a single item across the spectrum, like trivets or pie birds.

“As an Aries, fire and flames speak to me,” said Arlene Robillard, a purist who has one of the world’s largest collections of the company’s original color: Volcanique, an orange-red ombré sold in the United States as Flame.