French (probably) makers mark

[argentregime]

Hi all. No point in a photo here as it is easily described.

I have a watch which looks like early 19th century (but could be a late 19thC immitation) which I am fairly sure is French. I can see no hallmarks so it may be plated but there are two marks

a) The maker's lozenge with a simple capital "TL" and nothing else
b) A circile badly rubbed but which appears to contain the letters CHRYSOC... plus 2-3 letters unreadable. It could just be CHP.YSOC

I am not 100% convinced this is silver but any thought would be useful.

Thanks.