it is a PT case pocket watch. i think its in an art deco style.
i donot know the follew question:
1、when it was made ,maybe in 1930,before the Second World War?
2、the case was made in USA ? why the case without the case number?
3、the character of "vacheron&constantin" is Enamel ? PTcase with Enamel dail is rare in VC pocket watch ?
4、the diamonds in the case is origional ?