The actress penned a tribute to Paige Heard, who died in May.
She wrote on Instagram: “Yesterday was my mom’s birthday. They say the first one is the hardest. I hope that’s true.. although nothing will ever lessen how much I miss her or will miss being able to tell her happy birthday.
“Here’s to all the mamas out there.”
Heard shared the news of the death of her mother on May 3, when she wrote: “I am heartbroken and devastated beyond belief at the loss of my mom, Paige Heard.
“She left us too early, clasping onto the memory of her beautiful, gentle soul.
“She will be missed from the very depths of our hearts forever.
“Her unflinching, open heart made her the most beautiful woman I had ever known.
“It’s hard to imagine and even more difficult to say but I feel truly lucky to have been her daughter and been given the gift of having the light she shone on everyone, fall on me for nearly 34 years.
“This has been an unbelievably painful time but in that, I am reminded of what survives us all, love.
“The kindness, support and generosity my sister Whit and I have received from friends and family has been utterly soul-saving.”
Heard’s mother died months before Johnny Depp’s blockbuster libel case against The Sun’s publisher, News Group Newspapers, began in July.
Text messages between Paige and Amber Heard and between Paige Heard and Depp were read in court.