(CNN) -- A painting by pop artist Roy Lichtenstein, which has not been seen in public for more than 30 years, and a massive pearl once owned by Mary Tudor have been unveiled as the highlights of London's Masterpiece art fair.
The artwork, "Puzzle Portrait," was created by Lichtenstein (1923-1997) in 1978, before being sold directly to its current owner, who kept it out of the public eye for decades.
The super-sized pearl, which weighs 64.5 carats (258.12 grains), once belonged to England's Mary I (1516-1558). The monarch was painted wearing it in several portraits, now in the Prado in Madrid and the National Portrait Gallery in London.
"It is a true natural masterpiece," said Nazy Vassegh, the event's CEO. "It is one of the world's largest natural pearls, and on top of that it has royal provenance. Pearls of this heritage are very rare. It is part of history."
The jewel disappeared in the late 16th century, and was missing for hundreds of years, before being rediscovered in 2004; following extensive research, it has only recently been identified as the Mary Tudor pearl.
Organizers of the fair say the pearl and the pop art are likely to be among the most sought-after pieces for sale at Masterpiece 2013.
The only fair of its kind taking place at the height of London's arts and social season, the show is held in a purpose-built pavilion in the grounds of the Royal Hospital at Chelsea.
Held annually since 2010, Masterpiece offers shoppers and curious visitors the chance to get up close to -- and even take home -- museum-quality art and artifacts.
More than 160 dealers, galleries and workshops will display antique furniture and classic cars, precious jewelery, ancient sculptures and contemporary video installations.
"The idea is that there is a bit of everything, but that it is all pretty special," explained Vassegh. "We have works from the 6th century B.C. and even earlier, right through to a Bill Viola, and everything is of an extremely high quality."
Each work has been vetted by one of 26 committees of experts, to ensure the highest standards across disciplines, and some of the biggest names in art, from Albrecht Duerer and Nicholas Hilliard to Pablo Picasso and Joan Miro will be on view.