The Prince of Wales shared a new picture and described his wife as 'remarkable' in a touching birthday tribute on Instagram.

The Prince of Wales posted a birthday message for his wife, Catherine, Princess of Wales to social media on Thursday to celebrate her 43rd birthday.

Kate Middleton, who is celebrating her 43rd birthday on Jan. 9, has proven herself to be the shiniest jewel of the British monarchy. The princess is married to Prince William, heir to the throne.

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Kate, the Princess of Wales, turns 43 on Thursday, capping what was a tumultuous year for the mother of three and wife of Prince William. Kate, who was born Jan. 9, 1982, is expected to spend her birthday privately with William and their kids -- Princes George and Louis and Princess Charlotte -- at home in Windsor, England.

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Prince William praised the strength of the Princess of Wales after a turbulent year, offering a 43rd birthday wish on social media that described her as an incredible wife and mother.

Princess Kate is celebrating her 43rd birthday. Her husband, Prince William, honored the "most incredible wife and mother" in a new post.

Kate Middleton's 43rd birthday portrait was taken by Matt Porteous in Windsor Castle last summer. She is spending the day with Prince George, Princess Charlotte and Prince Louis.

Prince William is honoring his wife, Princess Catherine, on her 43rd birthday, calling her "the most incredible wife and mother."