Silver is a beautiful, lustrous metal, but both pure silver and its common alloys tarnish easily when exposed to the air. Tarnish is the unsightly black coating that forms on silver jewelry when it comes into contact with sulphur in the air. Contact with sulphur causes a chemical reaction that forms silver sulphide, which appears as a black layer on the surface of the jewelry. While this layer can easily be removed, it is best to prevent it from occurring at all by using tarnish resistant coatings.
Most jewelry available today includes a gemstone as a focal point for the piece. Sapphires and rubies are just two of the more popular gems used in this way. When mined, the gems are not faceted or ornamental. You must have them cut to bring out their brilliance and beauty. One technique used widely in the industry is to heat treat the gems before cutting or selection for use in jewelry. The process of heat treating the gems enhances the color of the gemstone. The color deepens and may change slightly. Heat treating occurs in two stages, the fancy burn and the blue burn. Most sapphires look best after the blue burn stage.
Precious Gemstones Ring
Precious gemstones are rare. They cost more than those considered semiprecious, and are ranked between 7 and 10 on Moh’s Scale of Hardness. Precious stones are less opaque and, when cut, sparkle in the sunlight. Emeralds and peridots are green gemstones that are considered precious. Although most are in other colors, some rare garnets, tourmalines, topazes and sapphires are green. The metal settings for these precious gems include sterling silver, gold and platinum.
Semiprecious Stones Ring
Semiprecious stones are softer than precious ones. They can be anywhere from a 4 to a 6.5 on Moh’s Scale of Hardness. Because of this, these stones are often carved into sculptures, beads and pendants. Semiprecious gemstones are less rare than precious ones, and cost less. They are more opaque and are often made up of layers in various shades of green. Semiprecious green gemstones include malachite, gaspeite, jade, jadeite, variscite, moldavite, jasper, adventurine and bloodstone.