I am particularly interested in Hufflepuff's cup and Ravenclaw's diadem that are said to have possessed powers. Were these artefacts that the owners held dear, and, as per their personalities, cast spells on at some point to give them magical power or were they specifically created just to be charmed, powerful objects? I'm not interested in what powers they possess (so it's not a duplicate of this question), just whether the objects were everyday household objects that had been charmed because they were significant to the founder or specifically crafted for the purpose
According to HP WIKIA (I know some users do not like quoting from this particular source) the artifacts are special in a sense because of the founders' interest in related subjects. Such as;
- The Cup: Helga Hufflepuff was brilliant with food-related charms and with house-elves, so the cup may have been the very first dining utensil at Hogwarts to assist in the magical transportation of food from the House-Elf Kitchens. The cup remained with Hufflepuff until the time of her death. (It was dear to her maybe?)
- The Locket: It was Salazar Slytherin's family heirloom. Everyone knows that now because in the last book it was defined with many details.
- The Sword: The sword of Gryffindor was made a thousand years ago by goblins, based on Godric Gryffindor's specifications. It had Gryffindor's name engraved on it. It was made for him based on his own liking.
- The Diadem: The diadem was not made by Rowena Ravenclaw but it was enchanted in a way to increase the wearer's intelligence. The reason why Ravenclaw picked this diadem specifically is not clear. It is also stated that Ravenclaw was a very intelligent woman, however she made a diadem to increase her intelligence even more. The reason behind why she did it is not clear either.