A tiny 19th century one-cent stamp from British colonial Guiana sold for $9.5 million in a two-minute-long swarm of bidding at Sotheby’s New York on Tuesday evening, the AFP reports. The so-called one-cent magenta beat a previous, $2.2 million record for a single stamp, which was set in 1996 by the Treskilling Yellow.

“This is the most expensive object in the world by weight,” auctioneer David Redden told the AFP following the sale, adding that it’s “almost the Mona Lisa of stamps.”

The stamp is octagonal in shape and measures just over an inch by and inch and a quarter. Former owners are said to have added their initials to the stamp’s reverse.

It’s the fourth time that this stamp has broken a world record. Initially created in 1856, it was first seen at auction in 1922. Bidding yesterday evening opened at $4.5 million and quickly escalated, selling to a anonymous phone bidder for just under the $10-20 million estimate.

It was last purchased in 1980 by murderous millionaire John du Pont and hadn’t been exhibited since 1986. Du Pont paid $935,000 for the stamp at the time.

The one-cent magenta was the result of a delayed shipment of stamps from England in 1856. The British colony’s postmaster then commissioned a contingency supply, of which, this stamp is the last remaining example.

Found by a Scottish 12-year-old in 1873, the stamp has since passed through the hands of French Fount Philippe la Renotiere von Ferrary and New York textile magnate Arthur Hind, among others.

It was consigned by du Pont’s estate. He died in 2010 while incarcerated for having killed Olympic gold metal winning wrestler Dave Schultz in 1996.