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Movement tier: unclassified · caliber Longines Cal. L899.5: ETA automatic with moon phase, 25,200bph, 64h PR, 25j; used in Master Moonphase; silicon hairspring, triple-calendar complications · 64h power reserve (2.7 days)
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
42 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

The moon phase disc is the most fragile and expensive component; inspect for chips or scratches under magnification before purchase.

Known issues in the market
  • Moon phase disc has a chip or scratch; even minor damage is visible every time the complication displays and is costly to repair.
  • Moon phase disc shows only one moon in the aperture when both should be partially visible at certain phases; the disc is installed incorrectly or has slipped.
  • Moon phase accuracy degrades if the disc mechanism has worn teeth; the disc should advance precisely one tooth per day.
AreaWhat to checkWhat is correctRed flag
dialMoon phase disc condition under magnificationDisc surface is unscratched; moon rendering is crisp with no chips at the edge of the moon figures; disc color is consistent with Longines press materialsAny scratch visible on the disc surface under a loupe; chips at the edge of either moon figure; disc with a different color rendering than the reference specification
dialMoon visibility and disc positionAt new moon the disc shows the void between the two moon figures; at full moon a complete moon is centered in the apertureMoon that is partially cut off at full moon; disc that is positioned asymmetrically so the moon is never fully centered; disc that advances inconsistently
movementCal. L899.5 moon phase gear trainMoon phase corrector pushpin (if present) advances the disc cleanly; disc advances one precise step per activationCorrector pushpin that does not advance the disc; disc that advances multiple steps per push; rough or grinding resistance when advancing the disc
Common legitimate replacements
  • Moon phase discs are available as spare parts but Longines-spec discs with the correct rendering are preferred; aftermarket discs may have a different artistic rendering.
  • Crown and pushers on the Master Moonphase must seal correctly to protect the moon disc from moisture; verify the crown screws down or seats firmly.
Expert resources: Longines.com Master Collection documentation for moon disc specification. TimeZone Longines forum for Cal. L899.5 moon phase service history and disc sourcing.

Authentication guide

Last reviewed June 2026

The triple-calendar moonphase with the L899.5 is the most complication-dense piece in the Master Collection. The moonphase disc and triple-calendar mechanism are the authentication focus.

Known reproduction risks

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LOW

The Master Moonphase is a niche collector piece without known reproduction risk. The main concern is incorrect moonphase disc from a generic ETA service kit.

  • Generic ETA moonphase disc vs. Longines-spec disc
  • Missing triple-calendar correctors in case band
  • Non-Longines movement visible through exhibition caseback

Dial variants by era

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EraDescriptionIdentifiers
2017 to presentTriple-calendar dial with day, date, month, and moonphase aperture
  • Silver or cream dial with Roman numerals
  • Day at 9, month at 3, date at 6 integrated with moonphase aperture
  • Moonphase disc visible at 6 o'clock
  • Central seconds
  • 42mm case, 48mm lug-to-lug, 11.9mm thick
  • Leather strap standard; no metal bracelet on this reference

Service part flags

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Moonphase Disc

Original: Blue disc with two moon reliefs and Longines-specified star field; advanced once per lunar day

Replacement tells
  • Generic ETA moonphase disc with different star density or moon size
  • Disc with incorrect background color (blue is standard)
  • Moon shape differs from catalog specification
Triple-Calendar Mechanism

Original: Independently correctable day, date, and month via correctors in the case band

Replacement tells
  • Missing corrector pushers in case band (indicates case donor or damage)
  • Correctors that do not advance the respective complication
  • Month disc with incorrect month abbreviation set or font
Roman Numeral Indices

Original: Applied Roman numerals; correct weight and finish for the dial color

Replacement tells
  • Printed Roman numerals instead of applied
  • Incorrect typeface for the Longines Master Collection specification

Case back markings

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2017 to present
  • Solid or exhibition caseback; exhibition shows L899.5 with Geneva stripes
  • Caseback engraved: reference L2.919.4.87.9, 30M water resistance
  • Cal. L899.5 designation on movement plate

Movement tells

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  • The L899.5 runs at 25,200 bph with silicon hairspring; magnetic resistance is expected and testable.
  • Triple-calendar complications require annual setting (full years do not have 31 days in every month); the watch may need manual date correction at the end of short months. The mechanism should advance correctly at midnight on long months.
  • The moonphase disc should advance cleanly once per day; any disc that skips, stalls, or makes noise is a service flag for the moonphase advance mechanism.
  • 64-hour power reserve applies; confirm with a full-wind rundown test.
  • The correctors in the case band allow setting day, date, and month without pulling the crown; any corrector that does not advance its complication indicates a broken advance lever, a known service point.
Sources: Longines Master Collection — official.

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