In Conan the Barbarian, Conan, Valeria and Subotai steal the legendary "Eye Of The Serpent" jewel from Thulsa Doom's Snake Cultists, and Valeria keeps it.
That got me to thinking about gems and jewels in Dungeons and Dragons: specifically, the lack of quests or adventures related to the recovery of legendary gems and jewels, and the absence of named jewels and jewelry. In D&D, most jewels and jewelry are immediately fenced and converted into cash, or, used as cash themselves. The jewels and jewelry treasures are usually described fairly generically, with, at most, the type of jewel or jewelry and the gp value disclosed. I can't think of very many ocassions where the jewels and jewelry were kept by the characters, for their own pleasure, or where the players discovered that the items had an interesting backstory.
This is unfortunate, particularly considering the classic image from the cover of the original AD&D players handbook, showing several thieves prying a huge gem from the eye of the temple's idol. Shouldn't those jewels have had some interesting name or backstory?
Magic Realm, one of my favorite games, has several named jewels and pieces of jewelry that the players can discover. Those include the "Eye of the Moon", "Blasted Jewel", "Dragonfang Necklace", "Eye of the Idol", "Glimmering Ring", "Glowing Gem", "Regent of Jewels", and the "Timeless Jewel".
I think it would be interesting to give backstories and names to the larger jewels and more valuable pieces of jewelry, and plant rumours periodically on where they may be found. Players may be more apt to keep those items if they have some interesting history behind them, or at least appreciate them more, prior to selling them off.