The number of jewels in a watch became a kind of status symbol and to some at least, an indication of quality and timekeeping ability. When one goes beyond 17 jewels, the use of cap jewels and, or, the jeweled mainspring barrel or main wheel come into play. One can determine if a movement uses the jeweled main wheel by counting the cap jewels.
Below is a photo which includes the escape and pallet jewels from a 19 jewel Vanguard. Note that there are no cap jewels (the tips of the pivots are visible). This would indicate that the mainwheel is jeweled. It would appear that all 19 jewel Model 92's have a jeweled main wheel.
The 21 jewel Model 92 is seen in 2 variations that we know of. Either both the escape wheel and the pallet arbor have cap jewels, or just the escape wheel is capped and the jeweled main wheel is used. There is some feeling in the watch collecting community that the 21 jewel Crescent St. was also made with the pallet arbor capped, with no cap jewel on the escape wheel, and a jeweled mainwheel. So far, we have not seen an example of this variation. Below you will see examples of both of the variations that have been observed to date. The top photo shows a capped escape wheel and no cap jewel on the pallet arbor. The bottom photo shows caps on both the pallet fork and the escape wheel.
In a 23 jewel Model 92, both the escape wheel and the pallet fork have cap jewels and the jeweled main wheel is used. The above photo, even though it is from a 21 jewel watch, shows this configuration. The photo below shows the escape and pallet jewels without the balance wheel. In this example, only the escape wheel is capped.
