If I am interpreting the colors correctly, it's a stainless steel back. If that is the case, the top is usually made of a lower Karat gold, like 10k or 14k.

Can you provide a photo of the back? It would tell me what the case is made of.

These are made by Jaeger-LeCoultre and have a similar valuation.

They won't have anything about that watch's history beyond what I told you as they have no record of what was done to USA watches. They only shipped the movements out of JLC CH, the case was made in the U.S.A. JLC CH was no records other than that of the movement.

Save your $.

Cal 480 is decent.

It's a caliber K480/CW, dates to about 1963.

If not, it's the outer arrow that would be the pry point.

If it says "use wrench XYZ" that usually indicative of a one-piece case. You'd need to remove the crystal and drop the movement out from the front.

It may or may not have a model name. You'd need to find it in an old catalog, I don't have them all.

I can date it for you and identify its case reference once you get shots of the insides.

Only the factory will be able to align a case serial number to a reference number.

I do not have the specs of crowns cataloged for each model. 6mm is however correct. A 0.2mm difference passes. They're not the same, but it's hard to notice.

I can't see it.