Rubies are actually among the most lustrous and durable of all gemstones. They are not as hard as diamonds, but they are tougher than many other gemstones like emeralds. This makes them a good choice, in practical terms, for a ring that is going to be worn for long periods (like an engagement ring). Though diamonds are more traditional, the popularity of rubies for engagement rings is increasing. They can serve as a departure from the norm and conjure powerful associations of passion, love and desire. They are commonly the gemstone of choice for the royal family, so there is attention around their validity as an engagement ring stone.