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The Encyclopedia of Horology

Wristwatch · Diving wristwatch

Longines 'Nautilus' Skin Diver Wristwatch, Ref. 6921-1

Partially verified

This is a Longines 'Nautilus' Skin Diver wristwatch, reference 6921-1, dated by the dealer to 1958. It features a stainless steel compressor-style case manufactured by Ervin Piquerez S.A. (EPSA) measuring 40 mm across excluding the crown, fitted with a bidirectional rotating bezel calibrated to 60 minutes. According to the seller, the watch is powered by a self-winding Longines caliber 19AS movement with central seconds. The black lacquered dial exhibits heavy mottled patina and aging, and is printed with 'Automatic' script, radium-lumed Arabic numerals at the quarters, luminous baton markers, and a broad-arrow hour hand.

Dial and case view of the Longines Nautilus Skin Diver reference 6921-1
Dial and case view of the Longines Nautilus Skin Diver reference 6921-1 — Pascal karp Watches Expertise. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.proantic.com
Category
Wristwatch · Diving wristwatch
Maker / attribution
Longines
Reference
6921-1
Catalogue / lot identifier
1828220
Source-reported date
1958
Country
Switzerland

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Identity and Case Construction

The watch is identified by the dealer as a Longines Skin Diver reference 6921-1, designated 'Nautilus' and attributed to 1958. It features a stainless steel case described as an EPSA (Ervin Piquerez S.A.) 'compressor'-style construction. Dimensions stated by the seller are 40 mm across excluding the crown and 13.5 mm in total thickness including the crystal.

Front-facing observation shows an external bidirectional rotating bezel with deep edge serrations, dot minute graduations, and Arabic numerals at 15, 30, and 45. The seller states that the case has a screw-down caseback with a logo and that both the case and movement are signed and numbered; however, rear and internal markings are not visible in the provided photo.

Evidence for this section
  • “model 6921-1—“Nautilus”—in stainless steel”
  • “EPSA (Ervin Piquerez S.A.) “compressor”-style case, screw-down caseback with logo”
  • “40 mm (excluding crown) x 13.5 mm (including crystal); the movement and case are signed and numbered”
  • “External bidirectional rotating bezel with deep edge serrations, dot minute graduations, and Arabic numerals at 15, 30, and 45.”

Dial and Hands

Direct visual observation reveals a black dial exhibiting significant mottled aging and patina across the surface. The dial features luminescent Arabic numerals at the 12, 3, 6, and 9 cardinal positions, paired with a broad-arrow hour hand, a baton minute hand, and a center seconds hand.

The seller describes the dial as a lacquered surface and reports the luminous material on the numerals and hands to be radium. No independent radiometric test or laboratory report is provided in the source to confirm this composition.

Evidence for this section
  • “Black dial displays significant mottled aging and patina across the surface.”
  • “Luminescent Arabic numerals at 12, 3, 6, and 9 paired with a broad-arrow hour hand, baton minute hand, and center seconds hand.”
  • “Beautifully patinated lacquered dial, luminescent (radium) Arabic numerals and hands”

Reported Movement and Production Context

According to the seller, the watch is powered by a self-winding Longines caliber 19AS movement with central seconds. While the seller notes that the movement is signed and numbered, the internal mechanism is not pictured in the listing.

The listing reports that this reference was produced in limited runs from 1958 to 1960 totaling approximately 500 pieces. Specific movement and case serial numbers are not recorded in the source text, leaving archival production records unverified.

Evidence for this section
  • “equipped with the 19AS caliber, central seconds hand, self-winding movement”
  • “the movement and case are signed and numbered”
  • “model produced by the manufacturer in very limited runs from 1958 to 1960 (approximately 500 pieces)”

Open research questions

  • What specific serial numbers are stamped on the case and caliber 19AS movement?
  • Can Longines archival extract records confirm the invoice date and destination for this specific reference 6921-1?
  • What specific logo and EPSA patent text are stamped on the exterior and interior of the caseback?

Source evidence

Recorded claims and source quotations for Longines 'Nautilus' Skin Diver Wristwatch, Ref. 6921-1
FieldSource-reported valueSource quotation
Model Reference6921-1“model 6921-1—“Nautilus””
Case MaterialStainless steel“in stainless steel”
Caliber19AS“equipped with the 19AS caliber”
Case Style and MakerEPSA compressor-style“EPSA (Ervin Piquerez S.A.) “compressor”-style case”
Dimensions40 mm x 13.5 mm“40 mm (excluding crown) x 13.5 mm (including crystal)”
BezelBidirectional rotating graduated to 60 minutes“bidirectional rotating bezel graduated to 60 minutes”
Reported Production Span1958–1960“produced by the manufacturer in very limited runs from 1958 to 1960”
Reported Total ProductionApproximately 500 pieces“approximately 500 pieces”
Caseback TypeScrew-down caseback with logo“screw-down caseback with logo”

Visible details

  • Black dial displays significant mottled aging and patina across the surface.
  • Luminescent Arabic numerals at 12, 3, 6, and 9 paired with a broad-arrow hour hand, baton minute hand, and center seconds hand.
  • External bidirectional rotating bezel with deep edge serrations, dot minute graduations, and Arabic numerals at 15, 30, and 45.
  • Mounted on a dark brown textured scale-pattern strap.

Research qualifications

  • Movement caliber 19AS and inner caseback markings are reported by the seller but not visible in the provided image.
  • Radium composition of the luminescent material is reported by the seller.

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

Proantic: Longines Nautilus "skin Diver" -1958-

Reviewed 2026-10-21 · Record a80e997789

Terms in this record

Glossary explanations for terms named in this object’s record.

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