I have set a 16 mm x  12 mm  Tourmaline cabochon in a fine silver setting.

The top of the ring measures just under 1" by 0.75" and the band size is just shy of a size 7 (US)
 
 
Please be aware that the size of jewelry in photographs can be deceptive so be sure to read the measurements carefully before you purchase.
 
 
I design and make all of my jewelry in my home studio in Texas.
 
For updates on new jewelry follow me on Instagram
 
https://www.intstagram.com/coldfeetstudio