The Duchess of Cambridge is known for her perfectly crafted sense of style , and that extends to her glittering accessories. Premarriage Kate Middleton wasn't really one for accessories, but having access to Queen Elizabeth II's jewelry vault can easily turn any woman into a bling-lover. (Plus, the queen reportedly told Kate that she needs to start wearing more of the family's priceless heirlooms in a bid to make her look more regal .)
We've tracked down the history of all the borrowed pieces that Kate has added to her working wardrobe, from diamond-encrusted brooches with deep meanings to tricky tiaras.
Source: Getty / Chris Jackson, Samir Hussein, Karwai Tang 
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.
Source: Getty / Chris Jackson, AFP, WPA Pool 
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.
Source: Getty / Samir Hussein, MJ Kim 
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.
Source: Getty / WPA Pool, Chris Jackson, Hulton Archive 
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.
Source: Getty / Chris Jackson, Oli Scarff, Chris Jackson 
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.
Source: Getty / Karwai Tang, Shaun Curry, AFP 
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. 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 from King George VI 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.
Source: Getty / Kypros , Splash News Online