The Duchess of Cambridge is known for her perfectly crafted sense of style , and that extends to her glittering accessories. A decade ago, Kate Middleton wasn't really one for major sparkle. But access to Queen Elizabeth II's jewelry vault could turn any woman into a bling-lover. Kate has been lucky to wear heritage pieces either as loans or as gifts, including her diamond-encrusted Royal Family Order of Queen Elizabeth II badge .
We've tracked down the history of all the special pieces that Kate has added to her wardrobe. From diamond-encrusted brooches with deep meanings to tricky tiaras, here's a look at the many diamonds the birthday girl has worn — so far.
The Halo Tiara
Kate's most famous piece of borrowed jewelry would have to be the Cartier "Halo" tiara that she wore for her wedding  day in 2011. The tiara was purchased from Cartier in 1936 by King George VI (the Duke of York) as an anniversary present for his wife, Queen Elizabeth the Queen Mother. She in turn gave it to Queen Elizabeth II on her 18th birthday, and it has remained part of her personal collection. It features 16 graduated scrolls set with 739 brilliants and 149 baton diamonds. The tiara has previously been worn by high-profile women of the royal family, including Princess Margaret and Princess Anne. However, the last time it was seen out publicly was with Princess Anne in the 1970s.
New Zealand Fern Brooch
The duchess was photographed wearing Queen Elizabeth II's fern brooch many times during her first official visit to New Zealand in April. The piece was originally given to the queen during her coronation world tour in 1953 and 1954. As what often happens with gifted items from subjects, the brooch was commissioned by a local Kiwi women's group that wanted to show appreciation for their queen. (The fern is an important New Zealand emblem.) The queen has worn it to many New Zealand-related functions, but Kate gets the very special distinction of being the first person to whom the Queen has loaned it out.
Princess Diana's Engagement Ring
One of Kate's most used pieces of jewelry also has a very sentimental meaning to Prince William. Kate's engagement ring famously belonged to Princess Diana before William used it to propose to his longtime love. After they got privately engaged, Diana and Prince Charles selected the engagement ring from the official royal jeweler, Garrard, in February 1981. It consists of 14 solitaire diamonds and a 12-carat oval blue Ceylon sapphire set in 18-karat gold. It was notable at the time since it wasn't custom-made (which royal engagement rings traditionally are) and was actually part of Garrard's regular retail collection. The ring was given to Prince Harry after Diana passed, and he eventually gave it to William.
The Maple-Leaf Brooch
Kate was loaned this maple-leaf brooch by the queen before Kate and Prince William embarked on their 2011 tour of North America. The brooch was originally given to the Queen Mother by King George VI in 1939, before they took off on their first Canadian tour, so there is a nice romantic connection to the brooch. Since then, the queen and Camilla, Duchess of Cornwall, have both worn the brooch during Canadian visits.
The Nizam of Hyderabad Necklace
The duchess doesn't normally wear that much jewelry, but earlier this year, the queen reportedly asked that Kate be given more access to the royal jewels to give her a "princess-y" makeover. Enter the Nizam of Hyderabad necklace, which Kate wore during a visit to the National Portrait Gallery (where she serves as a patron) in February. The necklace was given to the queen by (who else?) the Nizam of Hyderabad, as a wedding  present. He told the queen to pick out anything that she wanted from Cartier, and she selected this glittering number, which features a chain of 38 diamonds plus a center piece of 13 emerald-cut diamonds.
The Lotus Tiara
In December 2013, Kate wore her second-ever tiara when she attended an official event at Buckingham Palace while wearing the Lotus tiara. (Kate wore it again to a reception in 2015 .) Like most of Kate's borrowed jewels, the item originally belonged to the Queen Mother. The tiara was originally a necklace and was given to the Queen Mother as a wedding  present in 1923. George later had the item dismantled and worked into a tiara by Garrard. (This practice is actually pretty common among the royals, and Diana was famous for reworking royal jewels in interesting ways.) The tiara was eventually given to Princess Margaret, who wore it to many official events. It was also worn by Serena Stanhope when she married Margaret's son, Viscount Linley, in 1993. After Margaret passed in 2002, the tiara somehow ended up back in the queen's main collection and was loaned out to Kate.
The Cambridge Lover's Knot Tiara
In December 2015, Kate was able to wear a tiara beloved by Princess Diana. En route to a reception at Buckingham Palace, Kate gave a glimpse at the Cambridge Lover's Knot Tiara, which Diana wore on numerous occasions including while on tour in New Zealand during 1983. The piece, which is in Queen Elizabeth II's collection, features massive pearls, surrounded by diamonds, hanging ornately around the top of the tiara. Queen Elizabeth reportedly loaned the piece to Diana for her wedding  day; finding the piece too heavy, Diana wore a tiara that had been in her own family. The Cambridge Lover's Knot Tiara was originally commisioned by Queen Mary and was constructed by the jewelers at Garrard.
The Queen Mother's Fringe Earrings
For the 2015 Women in Hedge Funds dinner, Kate wore a pair of diamond and sapphire fringe earrings that once belonged to the Queen Mother (pictured in London during 1986). The Queen Mother was a great fan of sapphires and had many pieces in her collection, though it is not known how she acquired the fringe earrings.
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