Few dresses are as iconic as the one Marilyn Monroe wore to sing "Happy Birthday" to former President John F. Kennedy, and as it turns out, few are as expensive.

According to a new survey by WatchShop, Monroe's sleek performance dress is worth more than 1,000 times its weight in gold—literally.

Marilyn Monroe
Credit: Cecil Stoughton/White House Photographs, John F. Kennedy Presidential Library and Museum/AP

The dress was designed by Jean Louis, and Monroe had to be sewn into it. It was embellished with 2,500 crystals and was understandably shimmery and expensive even for the time.

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Last year, it was sold at Christie's in an auction for $4.8 million.

Based on this, the dress's weight (103 grams), and the price of gold, experts at WatchShop estimate that the memorable dress is actually worth more than 1,145 times its weight in gold.

In short—it's extremely expensive.