I suppose it's because of the Chopard name and maybe the relatively small diameter. Finding one in platinum was one of the luckiest things that ever happened to me in the watch world. I had the white gold/salmon dial and looked for years for one in platinum, but I never found one. In fact, I couldn't even get solid proof that Chopard actually made any of these in platinum. Then, as luck would have it, a friend/collector who lives near me happened to find one in PT. He bought it for himself, kept it for a few years, and then offered it to me. Brings a smile to my face every time I wear it (and it fits my small wrist better than any Lange except perhaps the old 35.9mm Emil Lange 1815 Moonphase). I think Chopard used these Metalem dials a few years before Philippe Dufour picked a similar Metalem dial for his Simplicity, too, so it's nice to know that Chopard wasn't trying to copy Dufour.