While doing a bit of research on jewels, I've decided - for the first time ever- to actually count the number of jewels in Rolex Cal. 3135. To my surprise, the total count is 40 - not 31 as marked on the auto bridge. Obviously there has to be a reason behind this- either I am not counting properly or some jewels are not to be counted :-)

1. barrel arbour jewel, lower
2. great wheel, lower jewel
3. 3rd wheel, lower jewel
4. inter. calendar pinion, lower
5. escape wheel, lower jewel
6. escape wheel lower cap jewel
7. pallet, lower jewel
8. balance wheel, lower jewel
9. balance wheel cap, lower jewel

10. barrel arbour jewel, upper jewel
11. auto driving wheel, lower jewel

12. balance wheel, upper jewel
13. balance wheel cap, upper jewel

14. balance wheel, roller jewel

15. auto reverse wheel 1, lower jewel
16. auto driving wheel, middle jewel
17. auto reverse wheel 2, lower jewel
18. rotor weight, lower jewel

19. date disc 'dummy' jewel
20. date disc 'support' jewel 1
21. date disc 'support' (side) jewel 1
22. date disc 'support' jewel 2
23. inter. calendar pinion, upper jewel
24. date disc 'support' (side) jewel 2
25. date disc 'support' jewel 3

26. escape wheel, upper jewel
27. escape wheel cap, upper jewel
28. second wheel, upper jewel
29. 3rd wheel, upper jewel
30. great wheel, upper jewel

31. rotor weight, upper jewel
32. auto driving wheel 1, upper jewel
33. auto driving wheel, upper jewel
34. auto driving wheel 2, upper jewel

35. pallet jewel 1
36. pallet jewel 2
37. pallet bridge jewel, upper
38. second wheel jewel mounted inside cannon pinion
39. minute wheel pinion bridge jewel
40. yoke / cam jewel

Feel free to email your comments.