So what does your average 20-something billionaire choose as the center stone of the perfect engagement ring? Well, if you're the founder of Facebook, worth $15.5 billion and your name is Mark Zuckerberg, the answer is the ever-romantic ruby. On Saturday - only one day after Facebook started to trade publicly with an initial valuation of $104 billion – Zuckerberg married his long-term girlfriend, Priscilla Chan, in a surprising backyard ceremony. Apparently, none of the guests even knew the couple was engaged. The 100 people in attendance thought they were attending a party to celebrate the bride's recent med school graduation. Zuckerberg announced his marriage to Chan in the classic Facebook manner. He changed his status from "In a relationship" to "Married to Priscilla Chan," and the status earned 1.36 million "likes" by Wednesday morning. Although no photos have been released of the Zuckerberg/Chan ring, it was described by a Zuckerberg publicist as a "very simple custom-made ruby engagement ring that was especially designed by Mark." Due to their rich red hue, rubies have always symbolized passion, romance and happiness. Other celebrities to have flaunted their ruby engagement rings include the likes of Princess Fergie and Jessica Simpson. Zuckerberg and Chan met at a Harvard party nine years ago when both were waiting in line to use the bathroom. They started dating shortly thereafter and Chan has been at Zuckerberg's side during his epic journey from inventing Facebook to dropping out of college to rising to billionaire status and beyond. The Zuckerberg/Chan ruby ring was not the only one to make news recently. The fine jewelry of fellow billionaire Lily Safra set auction records at Christie's Geneva last week. The auction's top lot was a 32.08 carat Burmese ruby and diamond ring by Chaumet, which sold for $6.7 million, a new world record price for any ruby sold at auction. The socialite and philanthropist's complete collection, called "Jewels for Hope," fetched an impressive $37.9 million with the proceeds going to dozens of charities. Visit Ben David Jewelers on Facebook Visit BenDavidJewelers.com