Superstitions and status symbols surrounding gems and jewelry are as old as human civilization. Although ancient jewelry was unlike anything we wear today, their owners and wearers attributed special qualities to them to denote one or more things.
In early societies, jewelry was worn as amulets to protect against bad luck and illness… From these myths evolves jewelry made into symbols thought to give the wearer control over fertility, wealth and love. Jewelry was worn for its magical properties.
Jewelry later came to denote human connection and commitment. Slaves were made to wear bracelets to show who they belonged to. Wedding rings symbolized the commitment two people had for each other. At one time in Europe only the wealthy and high-ranking church officials were allowed to wear gemstones. [Source]
It is, therefore, not surprising that when J.K. Rowling introduced Horcruxes in Harry Potter and the Half-Blood Prince, she chose jewelry items for three of the seven receptacles of Lord Voldemort’s fragmented soul.
Marvolo Gaunt’s Ring
Marvolo Gaunt’s gold ring on which the Resurrection Stone was set, was stolen by Tom Riddle (before he was Lord Voldemort) from a Gaunt descendant. The Gaunts, descendants of Slytherin House founder Salazar Slytherin and Cadmus Peverell, inherited the ring from the Peverell line without knowing the significance of the stone. In a flashback scene in Half-Blood Prince, Tom Riddle is seen wearing it while pumping Professor Horace Slughorn for information about Horcruxes.
Originally owned by Slytherin House founder Salazar Slytherin, the Slytherin locket is an elongated octagon made with gold with a stone inlay of a snake in the shape of the letter S. Like Marvolo Gaunt’s Ring, the Gaunt family inherited the locket (this time, via the Slytherin line). It was sold by Marvolo’s daughter Merope to Caractacus Burke, one of the original founders of the Borgin and Burkes antique shop, for far less than its value while pregnant with the child that she would later name Tom Riddle after the father who had abandoned them. A witch named Hepzibah Smith bought the locket from the antique shop.
Decades later, Tom Riddle was shown the locket by Hepzibah Smith whom he had befriended. Smith was found dead after Tom Riddle took the locket which he later transformed it into a Horcrux and hid in a seaside cave where it was stolen by former Death Eater Regulus Black, younger brother of Harry Potter’s godfather, Sirius Black. Much later, it stolen by Mundungus Fletcher from the Black family home and gave it as a bribe to Dolores Umbridge, Senior Undersecretary to the Minister for Magic.
In the film Harry Potter and the Deathly Hallows Part 1, using false identities, Harry Potter, Hermione Granger and Ron Weasley broke into the Ministry of Magic and snatched the locket from Dolores Umbridge. Ron later destroyed it with the Sword of Gryffindor.
Rowena Ravenclaw’s Lost Diadem
“Diadem” can be an ornamental headband, a royal badge or a half-crown (a tiara) worn by women.
The Lost Diadem was originally owned by Ravenclaw House founder, Rowena Ravenclaw. Her envious daughter, Helena, wanting to be wiser than her mother, stole it and ran away. At Rowena’s deathbed, she sent the Bloody Baron to bring Helena back. The Bloody Baron found Helena in a forest in Albania where Helena had hidden the diadem inside a hollow tree. Helena refused to return and was stabbed by the Baron who, in horror of what he had done, stabbed himself afterward.
Later, Tom Riddle charmed Helena’s ghost into revealing the location of the diadem.
J.K. Rowling did not provide a detailed description of Ravenclaw’s Diadem in the Harry Potter books and most people visualize it based on how it appeared in Harry Potter and the Deathly Hallows Part 2 — made with white metal (probably silver) shaped like a raven with its wings spread, encrusted with white crystals (diamonds?) and, at the center, a large blue oval stone (sapphire?) from which dangled two smaller blue stones.
Although the first Horcrux was destroyed in the second novel, “Harry Potter and the Chamber of Secrets”, the concept and definition of Horcrux was not introduced until the sixth book.
Although the olden and gem-encrusted Helga Hufflepuff’s Cup is made with precious metal and gems, it is not a jewelry item as it is not meant to be worn.
In “The Tale of the Three Brothers” narrated in “Harry Potter and the Deathly Hallows”, Cadmus Peverell is the second of three brothers who cheated death and was falsely rewarded with the Resurrection Stone with which he attempted to bring back to life the girl he would have married.