Did your grandfather participate in WW2?

Excellent research!

If the JLC paperwork gave you a serial number I can date the watch.

The stamping on the back is the manufacturer of the case. I'm not sure off the top of my head who that is. I'll post if I run accross it.

Most USA market cases were made by U.S. case contractors, in particular when the cases were made of 14k or gold filled.

This appears to be it. "Diamond Royale" model. The catalog is from 1968, original retail without the bracelet was $295.00.

The catalog reference would be 20R.

I tried to find the crystal number for you, but I couldn't find my catalog. If you can find a .pdf online for the GS Catalog, it may be listed there, but TV shapes are always very difficult to source.

Sorry can't be of help. The crowns are unclear. I'd imagine 5.0-5.5mm is typical.

You're welcome; I have those as used parts if Perrin doesn't.

The parts in question should be the same between 497 or 497/1....maybe ask Perrin why they'd be different, but I expect them to be the same.

This is the TV shaped case?

1951, 1953, 1953, 1954, 1954, 1956

That is when they were produced as a movement, which could be cased later.