The 'Zero Dark Thirty' actress wore the lavish Bulgari jewellery - which boasts a 65-carat centre stone - in honour of the late Hollywood icon at the 50th anniversary screening of her classic film 'Cleopatra' at the Cannes Film Festival in France on Tuesday, and she admits she was nervous about being entrusted with the expensive heirloom.
Jessica explained to People: "I didn't want to know how much it was worth. It was so thrilling to wear it, but I was overwhelmed too. It was a little scary."
However, the flame-haired beauty quickly overcame her anxiety after she put the piece on and after spending a day with the necklace she felt a kinship to the iconic actress, who died in 2011 aged 79.
She said: "I was the first person to wear it since Elizabeth. I felt as if I was able to spend the day with her today by wearing the necklace."
The extravagant Bulgari necklace was famously given to Elizabeth by her fifth husband Richard Burton after they fell in love on the set of 1963's 'Cleopatra', and Jessica, 36, says she became "captivated" by the historic Hollywood couple's intense relationship after reading a book about their romance.
She added: "I was captivated by what an incredible love story they had. And I loved Richard's famous quote about how 'Bulgari' was the only word Liz knew in Italian. I was just touched by everything about their love."