Sterling Silver Classic Square-rectangle Signet Ring.
Shiny polished or Oxidized & Brushed finish.
Top size : approx. 9*13 mm.
Fourth pic : Hollow back.
Fifth pic : 
Engraving-Custom Engraving-Letter engraving-Initials Engraving-Personalization
1-3 big letters or 1-10 small letters on top of the ring.
Which font would you prefer and uppercase or lowercase letters, I'll do my best to make as you dream of.
Another cool ring for engraving :
https://www.galbarash.com/product-page/solid
Unisex.