Forbes magazine has generated a list of the world’s top art collections. It strives to rank the collections by value but admits that there is no solid measure for a collections real-time value. The case of David Geffen seems to have given the panel the most fits. Some valued his collection at $2 billion; other a mere $400 million. All were impressed with his timing in selling work to Steven Cohen. Here’s how Forbes characterizes its own list:

Topping the ranks is Philip Niarchos, son of the late shipping magnate Stavros Niarchos and father of Stavros III, who was linked in the past to American heiress Paris Hilton. He is said to have the most valuable collection, worth at least $2 billion. Philip’s father began collecting art in 1949 and over his lifetime acquired many well-known masterpieces including Vincent van Gogh’s “Self-Portrait with a Bandaged Ear” and Pablo Picasso’s self-portrait “Yo, Picasso.” Since his father left him the collection, Philip has quietly added such contemporary works as Jean-Michel Basquiat’s “Self-Portrait” and Andy Warhol’s “Shot Red Marilyn.”

During our quest to pin down these extraordinary collections, we discovered a new fortune belonging to Esther Grether, a little-known Swiss cosmetics heiress whose 7.5% stake in Swatch and art collection of more than 600 pieces, including ones by Paul Cezanne, Salvador Dali and Francis Bacon, make her not only a billionaire but also the only woman in our list of top art collectors. She keeps the works in a printing factory that she converted, and where she also lives.

The LA Times’s Culture Monster blog summarizes the other top entries on the list:

Pinault came in second, with a collection estimated at $1.4 billion that includes 2,000-plus works by more than 80 artists such as Picasso, Piet Mondrian and Jeff Koons.

The Broads, Geffen and Ronald Lauder are ranked next, tied with respective collections said to be worth $1 billion each. […]

Among the other listmakers are Leon Black, Steven Cohen, Henry Kravis, Samuel Newhouse Jr. and Esther Grether, who is the only woman on the list.

Top Billionaire Art Collectors (Forbes.com)

Broad, Geffen Make Forbes’ List of Top Billionaire Collectors (Culture Monster)

Slide Show of top collectors (Forbes.com)