Enamel is powdered glass fused to metal at high temperatures, leading to a hard surface with vivid, permanent color. This process persists in fine jewelry because it works so well and doesn't need any revision.
Style Notes
Sterling silver resists the bending and minor impact of daily contact better than softer base metals, and the gold surface reduces exposure to moisture and friction. These two properties allow gold over silver jewelry to handle frequent wear without requiring careful handling.
Stone Story
Diamond's rating of 10 on the Mohs hardness scale means it resists scratching by nearly ever other natural material, a property that comes from the strength of its carbon-carbon covalent bonds arranged in a cubic lattice, which features a geometric structure that supports the hardness as much as the chemistry of the bonds.