United Kingdom Size 18G Heavy Stud to US: 8mm Snug Hoop

United Kingdom Size 18G Heavy Stud: Features a post thickness of 1 $\text{mm}$ (0.0394 $\text{in}$), hoop inner diameter of 0 $\text{mm}$, gemstone carat equivalence of 0.75 ct - 1.00 ct, and earring style Stud / Gemstone.

US: 8mm Snug Hoop: Features a post thickness of 1 $\text{mm}$ (0.0394 $\text{in}$), hoop inner diameter of 8 $\text{mm}$, gemstone carat equivalence of N/A (Hoop), and earring style Hoop / Lobe-Hugging.