The search for the matching jewel

I'm still not sure whether it was me, or a previous person that worked on the Felsa 690 currently on my bench. To my defense, I did not find any splinters, but still, it had two cracked jewels (and a broken escape wheel pivot). Now, individually sized jewels are "expensive-ish" and double so because I need to mail order them from either the US (Otto Frei) or the UK (Cousins); I know of no Canadian watch supply house that has individually sized jewels in stock. A couple of envelopes with assortments were way cheaper, but then you need to find just the jewel you need…

This is my trick. The assortments live in a petri dish, I put that on a cheapo video light as a backlight, and the green tape on the microscope monitor will get pencil marks for the 0.9mm outer and 0.12mm inner diameter I'm looking for. Then I quickly select some promising candidates and measure them precisely. For measuring on the outside I use my Mitutoyo electronic micrometer, which I see as a reference of sorts; for the inside I got two sets of pin gauges from Ali Express which according that Mitutoyo are exactly as promised: ±0.001mm). The two sets cover 0.1mm to 2.00mm in increments of 0.01mm and were very good value for money compared to the regular sets you buy on the likes of McMaster-Carr.

The hole in the automatic works already has a new jewel, and I have a couple of candidates for the escape wheel lower jewel, but first I'll have to wait for the new escape wheel so I can check for good fit is the left-over pivot I could measure may have worn. Also, this wheel sits between capped jewel pairs on both sides, so I'm looking for a balance-style domed jewel, not sure that the assortment even has them. My next bet is dozens of Swiss donor movements in various states of repair (sometimes just the plates) I bought years ago as a lot, and of course there is always the fallback of sending money to one of these supply houses.

So, no idea whether I have a matching one. But I just wanted to share this little trick, it makes sorting through a bunch of random jewels a lot simpler.