F.P. Journe Automatique Lune Nacre Ref. AL2 Boutique Platinum Blue Mother of Pearl Dial

Blue shell in platinum is the cooler of the two Nacre moon phase dials, and both were boutique pieces made in very small numbers. Mother of pearl behaves unlike any other material Journe uses, catching light in bands rather than evenly, and setting it around a moon disc gives the face two different kinds of movement at once. Neither dial has returned to the collection since, and shell has not appeared on anything he has built afterward.

The platinum case is offered at 40 and 42 mm. A whitened guilloché silver center sits inside an outer ring of blue mother of pearl, with the moon aperture at twelve and a large date beside it. Cold metal and cold shell make this the more formal of the pair, and the more difficult of the two to track down. Every dial is slightly different, since the shell is natural.