Though the relic rarely leaves its home in France, it made its way to St. Catherine of Siena while on tour.
Dozens of believers were there to see a leg bone fragment believed to have belonged to Mary Magdalene, who according to the bible was the first person to witness and announce the resurrection of Jesus.
For more than 700 years it has been housed in a cave in Southern France, where it is believed Mary Magdalene spent the final three decades of her life.
The visit to the Rialto church is part of a one-month California tour.
The woman who helped organize the tour, Paula Lawlor, made a pilgrimage to the cave two years ago. She said she received a miracle.
"When you have a miracle, you're not supposed to hide it," Lawlor said. "You want to tell people. You want them to be able to experience it and it feels like being able to do this tour, my desire to share this with others for them to have their own experience is coming true."
This is the second time the relic has made its way to the U.S.