Got this in a few days ago. This version of the Crestwood, dates at least to 1958, since the dial has the Durabalance symbol, and the movement is the 23 jewel, 730.
The case is 7502C and it is 14K white gold. According to the ad, it uses 6 diamonds for markers. This has been on my to get list for awhile, so I'm thrilled to have landed a nice example.
Yes 4912.
My yellow Saturn also has a 4912 case number.
Bother have size 8/0 movements.
I assume you have a different number case because it is a 13/0 movement that replaced the 8/0 model.