IIRC Sobral is usually signed. It's far too new for me to know much about it though. This is site for vintage and antique items, and this is awfully recently made by board standards.
This doesn't look like Sobral to me, but I haven't seen many pieces. BTW, Sobrol has been around since the sixties...Mom had a bracelet that was to die for and she gifted it to a student.
Sobral pieces can be truly vintage since the company is not new. I'd check their site to see if this kind of construction is used.