Last Updated on Wednesday, 07 April 2010 12:24 Written by GoldSmithWatchWorks Wednesday, 07 April 2010 12:09

• 7 jewels actuall means that the movement has a jewelled escapement – two hole jewels and two cap jewels (one each for each end of the balance wheel shaft), two pallet jewels and a roller jewel.
  
  Most common movements of this period were no jewel or one jewel on the bottom of balance shaft. The 7 jewel movement was introduced as a means of preventing wear caused by the high speed of the escapment. This setup was common in older pocket watches and pocket watch movements used for wrist watches of the same period. We find many Omega, Waltham, Elgin and other name branded wrist watch movements that were either pocket watch movements or re-designed pocket watch movements. It became the minimum for a quality movements.
  
  
• 15 jewels – this is a jeweled escapement with the 7 jewels previously discussed  plus additional hole jewels for the high speed wheel staffs of the running train.
  
  Protection was now added to the secondary high wear shafts. 15 jewels became the norm for a quality movement.
  
  
• 17 jewels – about the minimum in a decent watch today add hole jewels to each end of the centre wheel
  
  This is the norm-- what is required to protect all higher speed shafts. this also covered the center wheel.
  
  
• 19 jewels – adds cap jewels to the escape wheel
  
  
• 21 jewels – cap wheels to the pallet fork
  
  
  
• 23 jewels – mainspring barrel jewels (common in pocket watches)
• Above 23 jewels - complicated watches, like even the basic chronograph, have more parts; including wheels and staffs for registers and the wheels associated with the movement of the standard operating train to the sub regsieter wheels and hart cams.