I came across this link and was fascinated. I thought some of you might be as well. It was produced by Elgin--from the looks of it I'd guess in the late 30s or early 40s. It's 72 minutes long, but goes through sapphire jewel manufacturing from the boule to the finished jewels. Pretty amazing to see what's involved, especially when you can still pick them up for a few bucks (less in bulk).

Elgin Jewel Bearing Manufacturing Film

Evan, thanks for posting this, it is a very through explanation of past mass production techniques. I wonder how close current techniques are to these?

Re the date: the introduction says that the jewel production is for the needs of WWII. The end of the movie shows the face of an Elgin chronometer which includes "1943", which I assume is the date. Did Elgin military chronometers normally have their production date on the dial, or was that done for the movie?

Wow I just come across this video you posted Evan. I wondered why it was so long but after watching it I realized just how much work actually went into making them. Totally amazing thanks for sharing it.