What's the Tartan?

Two Glaswegians are discussing a wedding...

Two Glaswegians, Archie and Jimmy, are sitting in a pub discussing Jimmy's upcoming wedding. "Och, it's all goin' pure brilliant," says Jimmy. "I've got everything organized already: the flowers, the church, the cars, the reception, the rings, the minister, even my stag night." Archie nods approvingly. "I've even bought a kilt to get married in!" continues Jimmy. "A kilt?" exclaims Archie. "That's magic! You'll look pure smart in that. What's the tartan?" "Och," says Jimmy, "I'd imagine she'll be in white."