Rolex introduced the ref. 6610 in 1955, two years after the first Explorer. It was fitted with the updated, calibre 1030, a thinner, chronometer-rated automatic that allowed for a flatter caseback and a noticeably sleeker profile on the wrist. By contrast, earlier Explorer-type references used the thicker caliber A296, whose height required a rounded “bubble-back” case. The 6610 therefore occupies a pivotal place between the pioneering early models and the later, long-running 1016, combining vintage gilt-dial charm with a more modern silhouette.

The dial features radium luminous compound on the hands and hour markers, now aged to an attractive tone; a continuous printed minute track (chapter ring) that neatly frames the text and the iconic 3-6-9 numerals; and the “OCC” (“Officially Certified Chronometer”), the pre-“Superlative” wording used by Rolex before the SCOC designation that became standard on the 1016.

This example comes from the family of Alfred Nobel, having passed by inheritance to the present owner, distinguished provenance that adds cultural weight to an already important reference and sets this 6610 apart.

Originally sold in Stockholm in 1958, it is accompanied by its original Rolex guarantee papers, box, and chronometer certificate.