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The hipped three-facet crystal arching over the dial is the kind of detail that separates a Gruen Curvex Precision from the broader catalog of 1940s rectangular tanks, and on this Ref. 370-650 the gabled crystal is doing exactly what Frederick Gruen patented it to do, riding the dramatic forward curve of the case and refracting the cream dial through three distinct viewing planes as the wrist moves. In our opinion, the 370-650 is the cleanest expression of Gruen’s curved-movement concept in white gold filled, and the Wadsworth-cased example we have here is wonderfully honest from the gilt Arabic numerals on the dial right down to the Wadsworth signature stamped into the inner caseback.
The Gruen Watch Company was founded in Columbus, Ohio in 1894 by Dietrich Gruen, and by the 1930s it had become one of the largest watch manufacturers in the United States, building movements at its plant in Biel, Switzerland and casing them in Cincinnati for the American market. The Curvex line, first patented in 1935, was Gruen’s answer to the rectangular tank format the rest of Switzerland was producing with shrunken movements crammed into oversized cases. Rather than cap a small round caliber inside a long box, Gruen engineered a movement that was itself elongated and bent along its length, so that a full-size train could be housed inside a case that genuinely conformed to the wrist. The Ref. 370-650 is the wartime-into-postwar continuation of that program, with the model number stamped explicitly into the inner caseback at the bottom of the engraved block.
The caliber inside is the Gruen 370, a 17-jewel manually wound movement signed across the bridge in gilt lettering with GRUEN WATCH C and PRECISION CURVEX PAT stacked at the top, SWITZERLAND beneath, and SEVENTEEN 17 JEWELS with UNADJUSTED below the balance. The 370 is the architecture that earned Gruen its reputation as the American firm that could keep up with Swiss-only houses on engineering, with a movement plate that follows the longitudinal curve of the case rather than sitting flat across the back of the watch. The UNADJUSTED stamping is period-correct for the consumer-grade Curvex Precision line and does not reflect on accuracy in service, since the movement has been regulated in-house at OTTUHR. The movement serial reads D144731.
The case is signed on the exterior caseback with GRUEN above W. GOLD FILLED, and the inner caseback carries the full Wadsworth block verbatim: 7621 at the top, then CASED & TIMED IN U.S.A. BY, GRUEN WATCH CO. in print, Wadsworth in script, 10 K. GOLD FILLED, the case serial L356934, and the reference 370 650 stamped at the bottom of the block. Wadsworth was the Newark case-maker Gruen contracted for most of its American Curvex production, and the W. GOLD FILLED stamp on the outer back specifies the white gold variant of the 10k bonded layer, which reads cooler and more silver than the yellow gold filled siblings in the 370-series catalog. The case measures 23mm wide by 42mm lug-to-lug, with the curvex profile visible cleanly in side view as the case arcs forward across the wrist and the lugs sweep downward at either end. The case carries a soft scratch field across the back from decades of light wear, with the front edges retaining the sharp original line work.
The dial has aged into a wonderfully even cream tone with light freckled patina distributed across the surface, and it carries the Art Deco numeral set that defines the Curvex line, full applied gilt Arabic numerals 1 through 12 in the stylized period font with a slight tail at every digit. GRUEN sits stacked over CURVEX inside the upper center of the dial just below the 12, and SWITZERLAND prints at the bottom edge below the small-seconds register. The sub-seconds at 6 sits inside a square framed cartouche with PRECISION printed across the top of the box, which is the Curvex Precision dial signature in its full architectural treatment rather than the more common dial without the framed cartouche. The hour and minute hands are gilt leaf-style with central spines, and no seconds hand runs from center since the small seconds carries the running indication. There is no lume on this dial, which is correct for the era and the Precision designation.
We pair this Gruen Curvex on the original 18mm tan Buttero leather strap with white contrast saddle stitching and a signed OTTUHR steel buckle, sized to a 8.5-inch maximum wrist. The tan leather warms the cool white gold filled case and gives the cream dial a quietly grounded backdrop, and the saddle stitching echoes the period-correct strap convention for a 1940s dress tank. The strap can be re-spec’d at the buyer’s request if a darker leather or a fabric pairing reads better for the intended rotation.
Serviced in-house at OTTUHR and backed by our 2-year mechanical warranty, this Gruen Curvex Precision Ref. 370-650 is the kind of American-engineered Art Deco tank that gets quieter and more interesting the longer you wear it. For the collector who values curved-movement engineering and a genuine Wadsworth-cased white gold filled survivor over a re-cased or re-dialed reproduction, the combination of the patented Curvex architecture, the framed PRECISION cartouche over the sub-seconds, the hipped three-facet crystal, and the verbatim Wadsworth stamping makes this, to us, one of the more characterful 370-series Curvex examples we have handled this season.
