A Guide to Illinois Watch Co. size 12 Watches, Grade 506.
Run.
Date
From
To
Total
H/O
Jls
Adj.
Run.
Date
From
To
Total
H/O
Jls
Adj.
1
1911
2,368,601
2,368,900
300
O
17
3 Pos.
14
1915
2,783,251
2,783,270
20
O
17
3 Pos.
2
1911
2,386,631
2,386,710
80
O
17
3 Pos.
15
1915
2,799,541
2,799,550
10
O
17
3 Pos.
3
1911
2,386,761
2,387,000
240
O
17
3 Pos.
16
1916
2,889,901
2,890,200
300
O
17
3 Pos.
4
1911
2,391,001
2,391,600
600
O
17
3 Pos.
17
1916
2,890,501
2,891,000
500
O
17
3 Pos.
5
1912
2,406,121
2,406,150
30
H
17
3 Pos.
18
1916
2,896,001
2,896,100
100
O
17
3 Pos.
6
1912
2,437,101
2,437,700
600
O
17
3 Pos.
19
1916
2,903,081
2,903,100
20
O
17
3 Pos.
7
1912
2,473,001
2,473,200
200
O
17
3 Pos.
20
1916
2,903,701
2,903,750
50
O
17
3 Pos.
8
19112
2,494,001
2,494,040
40
O
17
3 Pos.
21
1916
2,905,501
2,906,000
500
O
17
3 Pos.
9
1913
2,550,701
2,551,200
500
O
17
3 Pos.
22
1916
2,945,651
2,945,700
50
O
17
3 Pos.
10
1913
2,580,601
2,581,000
400
O
17
3 Pos.
23
1918
3,312,581
3,312,700
120
O
17
3 Pos.
11
1913
2,585,001
2,585,500
500
O
17
3 Pos.
24
1918
3,401,701
3,401,800
100
O
17
3 Pos.
12
1914
2,623,701
2,623,770
70
O
17
3 Pos.
25
1918
3,424,101
3,424,500
400
O
17
3 Pos.
13
1915
2,701,601
2,701,700
100
O
17
3 Pos.
 
Total
5,830
 
Name
H/O
Estimate
Name
H/O
Estimate
Ariston USA [made for Marshall Field & Co. Chicago]
17 Jewels O.F.
290
Illinois [ The Spingfield Watch]
17 Jewels O.F.
2,490
Ariston USA [made for Marshall Field & Co. Chicago]
17  Jewels H.
30
Illinois Watch Co.
17 Jewels O.F.
120
Ariston Rated [made for Marshall Field & Co. Chicago]  
17 Jewels O.F.
70
Illinois Zodiac
17 Jewels O.F.
300
Wm. Barthmam New York N.Y.
17 Jewels O.F.
50
Precise
17 Jewels O.F.
50
Hallmark [ made for United Jewellers]
17 Jewels O.F.
1,850
     
Serial numbers used on this page by the kind permission of
Russell W Snyder
Grade 506 Movements found to date.
Grade 506 runs.
Last update 05/30/2020.
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.
Images of grade 506