On their hunt for horcruxes, they were chased by snatchers, Death Eaters were raiding a house nearby and in order to save Harry, she sent a hex his way and pulled out a jade stone wrapped in a hand-embroidered napkin that once belonged to her grandmother, she hid it in her back pocket whenever they wandered in the enemy territory so, they can use if it came down to it. The moment she saw Harry and Ron holding hands, she called for Harry, and yelled, "Catch!". It was instinct really, he caught the stone and both apparated. 