Improved Sale Value (formerly known as 'Precious') items are items that, when identified, sell to the merchants for a much higher price than normal. The Improved Sale Value modification only appears on blue weapons, offhands, and shields, and is an innate modifcation of the item. It is possible to find an 'Improved Sale Value' item with upgrades attached, but no 'Improved Sale Value' item will have any damage modifications.
Nightfall precious items have "Show me the Money" inscription instead of the old Precious title, and the mod itself has also been renamed 'Improved Sale Value'.
The current mechanism of how the game determines the value of an 'Improved Sale Value' item is unknown. Improved Sale Value items have a minimum value of 20 gold and are dropped everywhere in the game.