Yes in title that would be a perfect fit., but is that tiara still in the RF ? Because I think the reason why Queen Mary created the lover's knot tiara was to get her own version of the piece that she apparently liked. Also Kate would be lucky if she got a piece from the Cambridge emeralds (Princess Diana once got the choker). In her current hairstyle, a small tiara like the one she wore for her wedding would suit her fine. Princess Margaret & Princess Anne both wore that with great success when they were young princesses.
Yes, the Grand Duchess Vladimir tiara is still with the Queen - who wears it regularly in all 3 forms (empty, with pearls and with emeralds).
Made for Grand Duchess Vladimir, aunt of the last Russian Tsar Nicholas II, the tiara was smuggled out of Russia during the Revolution by a British diplomat. In 1921 it was sold by the Grand Duchess’s daughter, Princess Nicholas of Greece, to Queen Mary, who adapted the tiara to take fifteen of the celebrated Cambridge emeralds as an alternative to the original pearls. The tiara was inherited by The Queen from her grandmother Queen Mary in 1953.
The Cambridge Lovers Knot Tiara was designed and executed in 1913 by E. Wolff & Co. for the royal jewelers Garrards, who were commissioned by Queen Mary to create a tiara based on the design of one owned by her maternal grandmother Princess Augusta of Hesse, the Duchess of Cambridge, wife of Prince Adolphus, the Duke of Cambridge, who was the seventh son of King George III. It gets its name from the original Lovers Knot Tiara owned by Princess Augusta of Hesse, the Duchess of Cambridge, which was given to her by her family at the time of her marriage to Prince Adolphus in 1818. The original Lovers Knot Tiara was subsequently given as a gift by Princess Augusta to her eldest daughter Augusta Caroline at the time of her marriage to Grand Duke Friedrich Wilhelm of Mecklenburg-Strelitz.