Jewels and their many shapes and sizes

[SargentColon]

I have just acquired a collection of jewels and am attempting to sort them.

Measuring the diameter's is simple (Micrometer) but how do I measure the internal hole?

Also there appear to be multiple "designs" for any given jewel size. 

e.g. I have separated out 1.2mm jewels, by eye I can see three distinct inner hole sizes (could be more) looking even closer I can see two different depths of Jewel, and closer still the "recess" on one surface of the jewel has at least three different diameters.

Other than how to measure the internal holes, how important are the other dimensions I can see and are there more I have yet to realise?

Your help in this would be greatly appreciated.

[JohnR725]

I'm attaching a book with the tool for replacing jewels. The book it also lists various jewel sizes shapes styles etc.

for the inside hole sizes they've made plug gauges in the past. Occasionally they turn up on eBay. If you have an assortment of balance staffs you could measure the pivot and use those as plug gauges and get that reasonably close

Seitz book.pdf

[SargentColon]

thank you. I will take a look at this.

[SargentColon]

Had a good read of this document.

Thank you so much. This is brilliant and answers many of my questions.