As retailers shrink away from diversity, the iconic American brand has taken the opposite route—and outpaced the market.

His cable-knit cashmere sweater is well worth the investment. Inside, see the green Ralph Lauren Purple Label sweater Timothée Chalamet wore and find out where to shop it.

Okay, hear me out—this isn't your traditional fisherman sweater, but you can make a damn good excuse for Polo Ralph Lauren's ultra-soft, ultra-luxe cable-knit sweater when you feel how ...