As posted on the watch in the database, if in fact it is a westover (has anyone got an add yet please?)
Ok people. My friend 57vert and I have been trying to get to the bottom of the "Westover" crystal saga after, as in previous messages here, I found the G-S crystal that was noted by other members was incorrect and would not fit. So here is the full information we have found, hope it is helpful to some. Thanks again to Charles for taking the watch and spending hours searching to get this info.
So after EXTENSIVE research, here is the info for the Westover (or the model named as such on here).
First: There is NO GS crystal that will fit. We did not rely on the catalogs, Charles went trying crystal by crystal in the entire size range, AND THERE IS NO CRYSTAL.
Second: The BB MX2129 (186) definitely fits. Here's the weird thing, the crystal number usually indicates the size in mm. So, this crystal should be 21.29 X 18.6mm, but it isn't! ..........It actually measures 21.0 x 18.6mm. I think maybe this is where people get the GS CMX324-2 fits (21.2 X 18.7mm,) even though it has rounded corners and the watch doesn't. They possibly find the BB crystal fits, see the GS matches the dimensions, and just think it's a match, not realizing the size discrepancy because they didn't actually measure the BB crystal!
Third: The WC P12MA210 (186) definitely fits, 21.0X18.6mm