Grade 506, 17 ruby and sapphire jewels adjusted 3 positions, manufactured from 1911 to 1918 a total of 5,830 movements in 25 runs make up this grade. Model 4 size 12/14 open faced and model 5 hunter; bridge movements of medium to high quality, double roller and patent micrometric regulator. Open faced 5,800 in 24 runs and hunter 30 in 1 run.
Observations, The majority of movements have broad striped pattern demaskeening. The size 12/14 movements have a size 12 bridges and size 14 pillar plate and have a stretched enamel dials that are not recessed into the pillar plate, they require special cases. Hallmark watch were made for United Jewellers and came factory cased with The Hallmark Watch on the cuvette. Ariston USA and Ariston Rated watches made for Marshall Field and the cases are marked Ariston with the M F & Co. logo. The Illinois movements were marked The Springfield Watch on the cuvette and advertised as part of the Springfield Watch Series. Run 5 of 30 Ariston USA models are the only hunter movements in the 500 grades.
Variants, Two types of escapement bridges can be found, with the majority of movements having the two fingered bridge except Ariston and Ariston Rated models that have a full plate escapement.
Description, 17 ruby and sapphire jewels; oreide settings; adjusted to temperature, isochronism and 3 positions; spring tempered compensating balance with timing screws; double roller escapement; hardened and polished steel escape wheel; sapphire pallets and jewel pin; polished gold center wheel; patent Breguet hairspring; micrometric screw regulator; safety screw center pinion; concave and polished winding wheels; safety recoil click; demaskeened broad striped pattern; gold inlay engraving; unusually large dial is a special feature of the watch.