Princess Kate rewears Princess Diana necklace at state visit with Prince William

Princess Kate is continuing her return to royal duties as she recovers from her cancer battle.

The Princess of Wales joined her husband Prince William and father-in-law King Charles for a state visit by Sheikh Tamim bin Hamad Al Thani, emir of Qatar, in London on Tuesday. This was Kate's return to formal state visit duties after she completed her treatment for cancer.

Charles, who has also been battling cancer, and the emir inspected the 1st Battalion Welsh Guards while a military band played. Queen Camilla wasn't present for the outdoor event as she recovers from a recent chest infection, but she is expected to attend a lunch at Buckingham Palace.

Kate was dressed in a burgundy coat and matching merlot fascinator at the event, and she completed the look with a necklace previously worn by Queen Elizabeth II and Princess Diana.

This was Kate's latest public appearance after she announced in September that she has finished undergoing preventive chemotherapy. Later that month, she made her first major public appearance to attend church service with the royal family in Scotland.

Princess Kate makes rare public appearance after completing cancer chemo

In October, Kate joined William to meet with emergency services representatives and families of the victims of a mass stabbing in Southport, England. Kate also attended the Remembrance Sunday ceremony in London last month.

The Princess of Wales is set to host annual Christmas carol service at Westminster Abbey on Dec. 6. In a letter to guests of the service, she wrote that Christmas "encourages us to turn to love, not fear," and it "is this love which is the greatest gift we can receive. Not just at Christmas, but every day of our lives."

Princess Kate makes first public appearance at church service after finishing chemo

Kate in September said that she is "doing what I can to stay cancer-free" after completing chemotherapy but that her "path to healing and full recovery" is still "long."

"I must continue to take each day as it comes," she said. "I am, however, looking forward to being back at work and undertaking a few more public engagements in the coming months when I can. Despite all that's gone before, I enter this new phase of recovery with a renewed sense of hope and appreciation of life."

The Princess of Wales first shared her cancer diagnosis in March after King Charles III also announced in February that he was diagnosed with cancer after treatment for benign prostate enlargement. Last month, William told British media that the year has been "dreadful" and probably the "hardest" of his life.

"Trying to get through everything else and keep everything on track has been really difficult," he added.

Contributing: Sarah Young, Reuters; Taijuan Moorman, USA TODAY

This article originally appeared on USA TODAY: Kate Middleton attends state visit amid cancer recovery