The Oscar-nominee paid tribute to the actor during a tearful and moving appearance on Bravo's Inside the Actors Studio, which aired on Feb. 20.
"He was beautiful," Amy said, speaking to the audience and the show’s host, James Lipton. "He's a beautiful spirit and he had this unique ability to see people, to really see them – not look through them – he just really saw people. And he will be missed.”
Visibly shaken, the actress continued: “Sorry, I really… I just really loved him and I know so many people did. And I just don't know how much more I can talk about it right now. Sorry."
Amy, 39, had worked with Philip on two Oscar-nominated films: The Master (2012) and 2008’s Doubt (2008). Both stars received Academy Award nominations for their roles.
The actor was found dead in his Manhattan apartment on Feb. 2 from an apparent heroin overdose. He was 46.
Earlier this month, Amy attended his wake along with Joaquin Pheonix, Cate Blanchett, Justin Theroux and Michelle Williams.