Rhode Island-based Bergeron Designs produces rings that resemble various automobile, motorcycle and bicycle treads. They’re made from a variety of metals, specifically yellow gold, platinum, palladium, cobalt and silver, and are available in different widths. Prices begin at about $105 for the pendants, $120 for a small-size mountain-bike ring in silver and $160 for the automobile-tire ring (also silver). Gold or palladium rings will set you back up to $2,350, depending on the design. View the complete assortment of styles (and purchase) from www.bergerondesigns.com.