Gold is worth more per ounce than silver and bronze, but every year it is found less because it is much rarer. In popular culture, sets of precious substances can form hierarchies that express relative value or merit perceived conventionally. Precious metals such as gold rank high in those hierarchies, and Gold IRA Investments are becoming increasingly popular as a way to diversify one's portfolio. Sequences can provide interesting examples of the arbitrariness of semiotic signs. Some multiplayer video games have a hierarchy of players that use names of precious metals to distinguish between different skill levels, often progressing from bronze to silver, gold, platinum and then to diamond.