Makers Mark F with a dot in middle on my Ring. Thank you

Could anyone please tell me who made this ring? Also, I am not sure of the stone. Thank you for your time.

<img src=/uploads/db3169/original/1X/c706ce6a421d0c21f8eef853f851058a13edfe77.jpg">

<img src=/uploads/db3169/original/1X/d76decde5b69675d5289124d888073320ac5d4fb.jpg">

Its an interesting stone, looks to be gaspiete. This is not handmade, it is pressed out in a machine. thanks for sharing