Stephen Webster, the London-based jeweller who introduced his first men’s collection, Rayman, 17 years ago, agreed that the Japanese market is large. And, in South Korea, “they’ll even buy jewellery we make for women. They are completely comfortable buying something, if they like it,” he added.

Russian men on the whole are conservative but, Mr. Webster noted, they are the biggest spenders among his clients, favoring his custom-made, bejeweled Russian crosses, which sell for as much as $50,000. “The men are so macho, but a flamboyant cross is acceptable,” he said. “And like all men, they love the bespoke service. It’s like choosing the finish of a new car.”