Rubies are thought by some to contain the spark of life, so it’s no wonder that they are one of the priciest and most precious of all gemstones. Many believed July’s birthstone glowed from within and that gods and royalty used them to light their homes. (That also meant the stone couldn’t be stolen since it would shine through a thief’s clothing.) This brilliant red stone has long been associated with passion and desire and continues to be a popular choice for engagement and wedding rings; recently, Facebook founder Mark Zuckerberg gave his new bride a specially designed ruby ring. And not only do the gems inspire love and romance, but science as well: A synthetic ruby crystal was used to create the first laser.