Reference:16550: Difference between revisions

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The caliber 3085 is the single biggest change. On the 1655, setting the watch advanced both the hour hand and the 24-hour hand together; the 24-hour function was a day-night indicator and nothing more. On the 16550, the local hour hand moves independently of the 24-hour hand — arrive in a new time zone, jump the hour hand forward or back, and the 24-hour hand stays on home time. The 16550 is therefore the first Explorer II that works as a GMT in the conventional sense, putting it alongside the contemporary GMT-Master II 16760 that shares the same caliber.

The 16570 replaces the 16550 ~~in 1988 or 1989~~ and ~~runs through 2010 on the same 40mm case architecture and the successor caliber 3185, which is the 3085 with a slightly different rotor and minor internal changes. Most~~ of ~~the 16550's~~ visual ~~and functional~~ DNA ~~carries forward~~. What changes ~~between 16550 and 16570 is~~ the movement generation, the dial-surround treatment ~~on the Polar dial (white-gold surrounds on the 16550, black-painted surrounds on the 16570)~~, and the lume ~~composition that transitioned from tritium through the 16570's life~~. The 16550 is the ~~shortest-production Explorer II after~~ the ~~transitional references~~ and ~~before~~ the ~~modern 126570 shift~~.

The 16570 replaces the 16550 almost directly and keeps most of its visual DNA. What changes are the movement generation, the Polar dial surround treatment, and the lume era. The 16550 is the brief bridge between the 1655 and the long 16570 run.

==Production outline==

The ~~16550 runs for four years or less, with production start disputed between 1984~~ and ~~1985 and end disputed between 1988 and 1989~~. ~~The strongest editorial consensus places~~ the window ~~at 1985–1989; some writers round~~ to 1985–1988; an early handful of "1984" examples exists in dealer listings though whether those are genuine pre-production or misdated serials is not publicly settled. The end boundary is better-anchored around late 1988 or early 1989~~, with the 16570 launch absorbing production from that point forward~~.

The run is short and the exact edges are fuzzy. Most sources treat 1985–1989 as the practical production window, with the handover to the 16570 happening around late 1988 or early 1989.

Surviving 16550 examples typically fall in the R, L, E, X, and 8.4M–9.7M serial ranges, with dealer-catalogue consensus placing the cream-dial peak in the 8.4M–8.5M band and continuing examples documented into 9.6M. The earliest cream-dial examples show up on B-series serials from 1985; later examples into 1987 and 1988 show the same issue. That four-year window for the paint defect covers most of the reference's production rather than a narrow early band.

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 The caliber 3085 is the single biggest change. On the 1655, setting the watch advanced both the hour hand and the 24-hour hand together; the 24-hour function was a day-night indicator and nothing more. On the 16550, the local hour hand moves independently of the 24-hour hand — arrive in a new time zone, jump the hour hand forward or back, and the 24-hour hand stays on home time. The 16550 is therefore the first Explorer II that works as a GMT in the conventional sense, putting it alongside the contemporary GMT-Master II 16760 that shares the same caliber.
-The 16570 replaces the 16550 in 1988 or 1989 and runs through 2010 on the same 40mm case architecture and the successor caliber 3185, which is the 3085 with a slightly different rotor and minor internal changes. Most of the 16550's visual and functional DNA carries forward. What changes between 16550 and 16570 is the movement generation, the dial-surround treatment on the Polar dial (white-gold surrounds on the 16550, black-painted surrounds on the 16570), and the lume composition that transitioned from tritium through the 16570's life. The 16550 is the shortest-production Explorer II after the transitional references and before the modern 126570 shift.
+The 16570 replaces the 16550 almost directly and keeps most of its visual DNA. What changes are the movement generation, the Polar dial surround treatment, and the lume era. The 16550 is the brief bridge between the 1655 and the long 16570 run.
 ==Production outline==
-The 16550 runs for four years or less, with production start disputed between 1984 and 1985 and end disputed between 1988 and 1989. The strongest editorial consensus places the window at 1985–1989; some writers round to 1985–1988; an early handful of "1984" examples exists in dealer listings though whether those are genuine pre-production or misdated serials is not publicly settled. The end boundary is better-anchored around late 1988 or early 1989, with the 16570 launch absorbing production from that point forward.
+The run is short and the exact edges are fuzzy. Most sources treat 1985–1989 as the practical production window, with the handover to the 16570 happening around late 1988 or early 1989.
 Surviving 16550 examples typically fall in the R, L, E, X, and 8.4M–9.7M serial ranges, with dealer-catalogue consensus placing the cream-dial peak in the 8.4M–8.5M band and continuing examples documented into 9.6M. The earliest cream-dial examples show up on B-series serials from 1985; later examples into 1987 and 1988 show the same issue. That four-year window for the paint defect covers most of the reference's production rather than a narrow early band.