Its also a nod to history & some of the early 20th century pulp fiction that was part of what inspired D&D's creators.
There are all kinds of RW stories about people who plucked precious stones & metals from the tombs & statuary of conquered or "backwards" cultures (tomb raiders in Phaoronic tombs, Spanish Conquistadors in the New World, Imperial European armies roaming through Africa, etc.), and that became a common trope in adventure/pulp stories.
A classic historical example would be the Hope Diamond.
The Hope Diamond's history can be traced to a blue diamond named the Tavernier Blue, which was originally mined from the Kollur mine in Golconda, India, and was a crudely cut triangle shape of 112 3/16 carats (22.44 g). According to legend, before French merchant-traveler Jean-Baptiste Tavernier purchased it sometime in 1660-61, the Tavernier Blue was stolen from an eye of a sculpted idol of the Hindu goddess Sita, the wife of Rama, the Seventh Avatara of Vishnu. At some point in its history, the Tavernier Blue was recut into the now familiar Hope Diamond.