Materials: Natural stone/Precious Opal: 6mm Ring: Brass, [Plated] Nickel-free: Size 11, Free size Please be aware if you have allergies. Please refrain from purchasing if you are concerned about inclusions or chips unique to natural stones. Each item is carefully packaged with "care" for our customers. Please note that the color and shape may differ due to camera effects. Nickel-free plating is used. Therefore, this product is less likely to cause allergies compared to plated metal fittings. However, due to the characteristics of nickel-free plating, there are disadvantages such as uneven coloring, fine irregularities and roughness on the surface, and faster deterioration of the plating compared to plated metal fittings.