Rolex Oyster Observatory Chronometer 6210

Oyster → 6210

18K gold Rolex ref. 6210 with a silvered dial, subsidiary seconds, and Kew A Certificate text — Bonhams, 2018, lot 22.

The Rolex Oyster Observatory Chronometer ref. 6210 is a 34–35 mm, 18K-gold, hand-wound Oyster with subsidiary seconds. Documented Kew A movements are signed “Rolex Kew A Tested”; standard dials carry Observatory and Kew A wording. Bonhams identifies a 2024 example’s dial as a reprint without those inscriptions. Published accounts report 24 gold-cased examples, associated with 1954.

Core facts

Detail	Record
Model	Oyster Observatory Chronometer
Case	18K yellow gold, screw-down caseback and crown
Diameter	Auction catalogues give 34 or 35 mm
Movement	Manual wind, 10½ lignes; caliber naming varies by source
Display	Hours, minutes, subsidiary seconds
Date	No date
Reported gold production	24 watches, cased or released in 1954
Related Kew A reference	Steel Oyster Speedking 5056

Where it sits in the line

The 6210 was the gold-cased part of Rolex’s Kew A wristwatch program. Sources describe 136 certified movements, with 112 used in steel ref. 5056 Speedkings and 24 in gold 6210s. Christie's instead says 136 movements were submitted; James Dowling’s account, repeated by Hodinkee, and Vetroplastica give 145 submitted, 9 unsuccessful, and 136 certified. Those totals describe the wider test program, not 6210 production alone.

Production outline

The movements were tested before they were cased. Christie's dates movement 4162 to 1948 and says it was cased and sold in 1954. Bonhams dates movement 4156’s Kew A pass to 6 April 1951; Uhrenkosmos also places the 6210 release in 1954. Auction listings date individual examples circa 1951 and circa 1955; those are lot estimates, not evidence of separate production runs or the endpoints of the 6210 series.

Vetroplastica lists 1949–1951 for both the steel 5056 and gold 6210, alongside the later casing date reported by Christie's and Dowling. Its table does not say whether the range dates movement production, testing, or finished watches.

Published accounts report 24 gold watches. Hodinkee attributes the number to James Dowling, who said Rolex confirmed production and case numbers in a letter; Christie's cites Dowling and Hess’s The Best of Time. Specialist sites repeat the figure. The accessible sources report this correspondence but do not reproduce the Rolex records.

Movement notes

The 6210 is manual wind, with a 10½-ligne movement signed “Rolex Kew A Tested.” Christie’s calls the movement Cal. 10.5; Uhrenkosmos describes it as a selected Cal. 700; Vetroplastica says it uses a Cal. 700 base with some Cal. 720 components. Bonhams calls individual 6210 movements Cal. 720. The Movements page lists generic Cal. 720 as automatic; keep the auction label attached to its lot until factory records clarify the Kew movement name.

The trial movements differ in present condition. Bonhams reports that the balance in movement 4156 had been changed. Koller says movement 4160 later received a new balance and balance cock; its 2026 listing describes movement 4185 with its original Guillaume compensation balance and polished, bevelled steel cock.

Bonhams 2018, lot 22: movement 4156.
Bonhams 2024, lot 19: movement 4161.

Dial map

The documented silvered dials have applied markers and subsidiary seconds at six. Christie's describes applied gold Arabic numerals; Antiquorum and Bonhams describe baton markers. The Kew A dial wording includes “Observatory Chronometer” and “Kew A Certificate,” with the latter printed in red on the Bonhams 2018 example.

Bonhams’ 2024 watch has a reprinted dial. It reads “Rolex Oyster Chronometer” without “Observatory” or “Kew A Certificate.” Bonhams identifies it as a reprint, so it belongs under later dial condition rather than factory variants.

Bonhams 2018, lot 22: silver dial with Kew A wording.
Bonhams 2024, lot 19: reprinted dial without the Kew A text.

Hand descriptions also vary by lot. Antiquorum records yellow-gold dauphine hands; Bonhams 2018 describes gilt dagger hands with luminous inserts; its 2024 reprint example has gilt lance hands. The available examples show three hand descriptions without a production sequence.

Case, bezel, crystal, and crown

The catalogued diameter ranges from 34 to 35 mm. Christie's calls the case circular and water-resistant; Antiquorum describes a three-body case with an inverted bezel and concave lugs; Bonhams calls its examples tonneau-form. Catalogues differ in their case terminology and do not establish separate case designs. They describe a screw-down caseback and crown. Crystal material is not consistently reported.

Bracelets, end links, clasps, and packaging

Auction records mostly show the 6210 on leather. Koller’s 2025 listing describes a Bucherer gold bracelet as an alternative to a leather strap on one sale watch; factory supply and original fitment remain unproved. The cited records give no verified bracelet reference, end-link number, or clasp code.

Bonhams’ 2024 lot lists a Rolex box as an accompaniment. That record gives no evidence that the box was made for the 6210 or accompanied it at original sale.

Historical market and auction record

The table lists six auction appearances through June 2026. Five case numbers are visible; Bonhams masks the last two digits in its 2018 record, so that lot may overlap with another sale. Koller’s 2025 catalogue says four examples had been offered; its 2026 listing says five before the current sale. Six listings do not establish six individual watches.

Sale	Case / movement	Record
Christie's Geneva, 16 Nov 2009, lot 188	97'461 / 4162	34 mm; applied gold Arabic numerals; catalogue dates movement to 1948 and casing to 1954
Antiquorum Geneva, 27 Mar 2011, lot 108	97476 / 4157	34 mm; baton markers; dauphine hands
Bonhams London, 12 Dec 2018, lot 22	974** / 4156	35 mm; Kew A dial; balance reported changed
Bonhams, 12 Dec 2024, lot 19	97473 / 4161	35 mm; reprinted dial; Rolex box listed
Koller Zurich, 24 Jun 2025, lot 2860	97457 / 4160	35 mm; later balance and balance cock; Bucherer gold bracelet listed as an alternative
Koller Zurich, 23 Jun 2026, lot 2860	97463 / 4185	35 mm; Kew A dial; Guillaume balance and polished, bevelled cock described as original

The numbers above are reported as case numbers. James Dowling’s 6210 is reported as case 97458, described in his letter as the fourth gold-cased watch. The five-digit numbers fall outside the six-digit ranges in generic serial charts. Published records do not map them to those charts.

Gallery

Bonhams 2018, lot 22: full dial and case.
Bonhams 2024, lot 19: reprinted dial.
Bonhams 2018, lot 22: movement 4156.
Bonhams 2024, lot 19: movement 4161.

Sources