Late last year, Rebecca Minkoff set about renovating a 100-year-old house she had just purchased in Clearwater, Florida, the gulf town where she grew up. A hands-on designer, Minkoff happily immersed herself in the nitty gritty of the home makeover. (“If the toilet parts arrive in the next couple of weeks, I’ll be done,” she says during a recent interview with WWD.) And when she was looking for stone for her kitchen, she called…