The Panerai reference 6152/1 is the military diving watch that established the Luminor case, with the crown-protecting device whose patent was issued in 1955. Its large stainless steel case measures 45 mm wide and 19 mm thick on a circa 1955 example catalogued by Sotheby’s, and 47 mm on a later example sold by Phillips. Compared with the earlier ref. 6152, the case is slightly larger so it could take either the hand-wound Rolex calibre 618 with 17 jewels or the Angelus calibre 240, which shows small seconds at 9 o’clock. Dials are signed Panerai and use a sandwich construction with Arabic and baton indexes, while the later Luminor dials use a tritium-based luminous compound.

The 6152/1 was produced for the Italian Navy. According to Phillips, Rolex made 500 examples for Panerai in 1955, all supplied to the navy, while Sotheby’s cites about 300. Panerai then added its crown guard, which gave the “Luminor Case” its name, and later produced small runs with Angelus 240 movements. The brand registered the LUMINOR trademark in 1949, but the tritium-based Luminor compound only became available around 1965, after Switzerland banned radium-226 in watches; Phillips notes tritium was far safer than the radium used before. Some of these watches were presented to the families of recipients of the Gold Medal of Military Valour from the Second World War.

Collectors regard the 6152/1 as one of the key vintage Panerai references, because it combines the Rolex or Angelus movement, the patented crown guard and Italian Navy provenance. Prices reflect this: at Phillips Hong Kong, a 6152/1 with Angelus 240 movement and Luminor dial, described as the earliest known with that dial, sold for HK$1,638,000 against an estimate of HK$240,000 to 480,000. Signé Magazine reported another example selling for HK$1,260,000. Sotheby’s set a vintage Panerai record of CHF 425,000 in 2014 with a 1955 Luminor, according to Signé Magazine. The reference 6152/1 is no longer produced; its crown guard and name live on in the modern Panerai Luminor collection.