
The dress has now gained its own Wikipedia entry…
“The pink dress was auctioned at Profiles in History on 11 June 2010, with an estimated price of between $150,000 and $250,000 and described as ‘the most important film costume to ever come to auction’. The dress ultimately sold for $370,000.
Travilla’s notes reveal that she wore two identical copies in that scene as it took a long time to shoot and the dress being floor length was very prone to getting dirt on it. Due to the fact there was no digital retouching back when the movie was filmed, Travilla had to get 2 dresses made so Monroe could change into the spare one when the one she wore showed dirt.

‘Lot 832: Marilyn Monroe pink satin gown from the ‘Diamonds are a Girl’s Best Friend’ number in Gentlemen Prefer Blondes. This pink satin gown was worn by Marilyn Monroe as the gold-digging ‘Lorelei Lee’ in one of cinema’s most memorable song and dance sequences as she performed ‘Diamonds Are a Girl’s Best Friend’. This Travilla-designed pink silk satin strapless gown features black satin lining on the oversized bow attached at back. Features integral brassier with rear zipper closure (concealed with bow overlay) and interior Fox cleaning tag. Also comes with the original pair of screen-worn opera-length tubes worn over Marilyn’s arms (gloves are shown for display only) and pink satin belt with ‘M. Monroe A-698 1-27-3-7953’ written on the inner leather lining. Originally designed to be a two-piece garment, this lot features an additional bonus having the original top made for this dress (featuring interior bias label handwritten ‘1-27-3-7971 M. Monroe A 698-74’) that was not used in the production. This design was discarded due to the top and skirt separating when Marilyn raised her arms during the number. The gown exhibits slight toning in areas, common in silk garments from this era; otherwise in fine condition. The leather backing on the belt is cracked and missing in areas and silk exhibits fraying on edges. Marilyn’s public appearance dress worn at President John F. Kennedy’s birthday tribute sold at auction in 1999 for an astounding $1,267,500. This remains as the single most important screen-worn gown in film history to ever reach the auction block. Indeed, Marilyn Monroe’s ‘Diamonds Are a Girl’s Best Friend’ performance has reached such an iconic status that several notorious entertainers have copied it—right down to the pink strapless gown! This is the only known example to survive.'”