A Heart of Fire was a shining, red glowing stone from the planet Kiffu. Some of the more prized Heart of Fire stones were also blue, making them worth more than their red counterparts. On Kiffu, it was tradition to give the stone to someone you loved and cared about. It was said that the stone held a little of the spirit of both the giver and the receiver. Jedi Master Quinlan Vos gave a Heart of Fire to his Padawan Aayla Secura for her thirteenth birthday. When Aayla grew up and met Xiaan Amersu, she gave it to her. When Quinlan suffered from amnesia and returned to the Jedi Temple, Xiaan gave it back to Quinlan.
Boba Fett gave a Heart of Fire pendant to his wife, the Kiffar bounty hunter Sintas Vel, who kept it with her for many years, up to her disappearance. In 40 ABY, Boba asked his granddaughter Mirta Gev, who was one-fourth Kiffar, to try and read the stone via Psychometry to see what happened to Sintas. Mirta replied that since she was not a full-blooded Kiffar, she couldn't do it. Boba and Mirta eventually found a former Jedi posing as a Kiffar to read Mirta's half of the stone, and with it they found a lead that lead to the revelation that Sintas was still alive, albeit encased in carbonite.
After Boba and Mirta recovered the carbonite slab containing Sintas Vel from the government of Phaeda, they revived Sintas on Mandalore. Even though she was blind and amnesiac upon wakening, Sintas immediately asked for her Heart of Fire pendant. Mirta turned over her half the stone over to Sintas, who remarked that it felt different. Later on, Boba would buy her another, larger Heart of Fire, this one containing all his memories since he had left her. Boba presented her with the stone shortly before their granddaughter's wedding day, and although she declined the stone at first, Boba insisted she keep it if she ever wanted to "catch up". Sintas then proceeded to read the stone after Mirta had married Ghes Orade.