* The Sorting Hat: Though not technically a jewel, it's a magical item with a long history and is considered quite valuable. It's likely made of a material that's both durable and able to hold magic, which could be considered comparable to a precious metal or stone.
* The Golden Snitch: Made of pure gold, the Snitch could be considered a jewel due to its material.
* The Triwizard Tournament: The Tournament involves many treasures and valuables, including the Triwizard Cup itself, which is a very old and valuable artifact.
However, it's worth noting that Rowling primarily focuses on the magical elements of the world, rather than the monetary value of possessions.
Therefore, while there aren't direct mentions of jewels, there are certainly valuable objects that could be categorized as such. The focus, however, lies on the magic and the narrative, rather than the material value of these items.