This initial ring was originally an antique stick pin that’s been refashioned for a more stylish, modern wear. The G (or possibly C) is set in silver with rose-cut diamonds. The back of it is gold and it sits atop two 18k rose gold bands. Parts of the 10k stick pin were used to reinforce the bands, saving the ghost of the stick pin’s past as a remembrance of how it was once worn in a bygone era. 
Size: Approx. 5.25/5.50 US. Due to the very wide band this may fit more snug/uneven. 
Weight: Approx. 2.33g
Hallmarks: None (acid tested). 
Materials: 18k rose gold, 10k gold, silver, rose-cut diamonds.