1950s Angelus Rare "Dato 12" Split-date Calendar in 14K Yellow Gold

Angelus, rare "Dato 12", split date calendar in 14k yellow gold, circa 1950s.

It is Cal. 255 powered, an improved version of the rare in-house chronograph movement Cal. 250. It has a unique mechanism that splits the date into 10's and 1's. After 31 days, the date does not change to 1 so it needs to be manually adjusted by the 9 o'clock. Although inconvenient for a calendar watch made in the 50's, its unique mechanism and unique dial design still make this watch a must-have item. It is also in well-preserved condition that further enhances the rarity of this piece.