Rubies are the gemstone variety of red corundum, the same mineral that is sapphire in any other colour. As such, they have a hardness equal to that of sapphires (9) and their resistance to chipping and scratching makes them the ideal choice for use in jewellery. Rubies are one of the most expensive gemstones available today and are mined in Sri Lanka, Myanmar (Burma), Thailand, Vietnam, China, Afghanistan, Kenya and Tanzania. A number of ruby characteristics should be examined before purchasing a ruby: