The Art Deco-inspired tiara that Meghan Markle wore on her wedding day is a fine example of how the Royal Family re-purposes and updates its jewels. Known as the Queen Mary tiara, it was designed and crafted specifically to showcase the large, central brooch that is set with an impressive round diamond, surrounded by nine additional brilliants. This brooch was a 1893 wedding gift to Princess Victoria Mary of Teck, who later became Queen Mary, and it is detachable from the tiara. The brooch was given by the County of Lincoln, and is just one of many she received on the occasion of her marriage.
By all accounts, Queen Mary particularly enjoyed jewelry. She commissioned the tiara to fit the County of Lincoln brooch in 1932, which explains its sleek styling to complement the fashion of the times. She rarely wore the piece in public, and in fact owned at least three more bandeau-style tiaras. Upon Mary's death, the tiara was bequeathed to Queen Elizabeth II in 1953. Meghan Markle was the first woman to wear it publicly in 65 years. It was loaned to her by the Queen, and at this time it is unclear whether it was a temporary or permanent loan.
One notable addition that does not appear in the photograph -- the tiara was mounted on a thin, black velvet-wrapped band that disappeared into Meghan's hair, so that it would rest more comfortably on her head.
For all of its magnificence, this tiara is definitely considered one of the smaller, lesser tiaras among the jewels of the Crown. If you'd like to do a deep dive into the collection, I enjoy the blog www.orderofsplendor.blogspot.com that honors "all things elegant and entertaining in royal fashion," and my go-to reference is the 1987 book "The Jewels of Queen Elizabeth II: Her Personal Collection" by Leslie Field.