They use IP Plating which stands for Ion plating.
1 micron of 18K Gold or Silver, plus e-coating which qualifies it to pass waterproof tests.5 mm wideEach hoop weighs 6 grams (considered medium weight)Earrings are 100% nickel-free and cadmium-free." Luv Aj Amalfi Tube Hoops Gold.Outside Diameter: 2"" (50 mm)Tubing is 4.