The most valuable object to have sunk with the Titanic wasn't the Heart of the Ocean necklace from the movie (of course), but rather a Neoclassical painting titled La Circassienne au Bain. Painted by Merry-Joseph Blondel in 1814, this colossal artwork met its watery fate aboard the ill-fated ship. The surviving owner, Swedish businessman Mauritz Håkan Björnström-Steffansson, certainly knew its worth, filing a claim for a staggering $3M (in 2023 dollars). (via Kottke)
When or where Björnström-Steffansson initially acquired La Circasienne au bain is unknown. Following his studies at the Stockholm Institute of Technology, where he focused on chemical engineering, he was enroute to Washington, D.C., to continue his studies on a scholarship awarded by the Swedish government when he boarded the Titanic. It could be inferred that he perhaps brought it with him on the voyage as something to ultimately help furnish his accommodations; or, alternatively, he may have brought it as capital in case of need.
It is unknown how much Björnström-Steffansson's claim for Blondel's La Circasienne au Bain was settled for, but in total we know that following negotiations the total settlement paid out was $644,000, or approximately $19.6 million today. Ironically, the loss of Blondel's 1814 painting has helped to keep his name and his practice alive over the centuries, as with each anniversary of the Titanic's fateful first and last voyage La Circasienne au Bain is brought to light once more as the single most expensive item to go down with the ship.