While there was tons to see at San Diego Comic Con, our eyes were only on the mega-watt rock the bride-to-be was wearing when she showed up for a Facebook Live chat with Entertainment Tonight and her co-stars (which included her new fiancé! "It's over a hundred years old," Tulloch said of her gorgeous vintage sparkler."The diamond is from the 1890s, and the setting is from 1915, which is the year my grandfather was born." Too sweet, right?!"It's pretty public now that I'm dating David, so that's kind of out of the bag," Tulloch confirmed in an interview."We were hiding it for a long time, but now everybody knows." And now everybody knows that these two cuties are taking their relationship to the altar!Tulloch engagement ring is no ordinaryring as its diamond is a 1980s valuable rock whose setting date is 1915 the year of birth of Tulloch’s grandfather.