The singer's father Daniel passed away unexpectedly as his daughter celebrated her engagement to boyfriend David Foster.
Taking to Instagram, the American Idol runner up shared a snap of her gorgeous diamond ring, and explained how she showed it to her father moments before he passed away.
"[It] was the last thing I showed my dad before he passed and makes me smile when I look at this as a reminder of our last conversation," the 34-year-old bride-to-be said.
Scorpion actress Katharine said 'yes' when 68-year-old superstar producer and Asia's Got Talent judge David got down on one knee when they were holidaying in Italy last month.
"My dad was so happy for me," Katharine said, before confirming her engagement and tagging her fiancé. "It’s been a hard week. Lots of tears but I want to thank my friends and family for all the love and support.
"And now I’m ready to share with all of you what has been my sunshine amongst this painful loss. My love wisely said to me the other day that “death is the only thing that is 100 percent inevitable and the thing we are least prepared for.” So today we’re celebrating life and not forgetting love.
The couple have known each other for years before becoming romantically involved.
David is a 16-time Grammy award winning producer, having co-written hits such as Earth, Wind & Fire's "After The Love Has Gone," and produced Whitney Houston's epic anthem "I Will Always Love You".
"We're very close friends, and we've been friends for a long time" she said previously.
"I'm really, really fond of him, and I think he's an incredible person. I've known him since I was 21 years old, you know? He produced my first single. So he's been really good to me. People can say whatever they want."