The answer is: An onyx

Exo 28:9 - to be part of the priestly ephod

In Exodus 28:9, we encounter the fascinating detail about the 12 stones that were to bear the names of the sons of Israel, specifically, an onyx stone among them. This isn’t just random selectiveness when it comes to gemstones; every stone possesses unique characteristics and is laden with symbolic meaning.

The use of onyx is particularly interesting. Historically, onyx has been associated with strength and protection, which makes perfect sense for its role in the priestly garments. The high priest was tasked with representing the people before God, embodying both spiritual and physical dimensions of protection and guidance. By wearing the names of the tribes, he literally carried them close to his heart, emphasizing the personal connection between the people and their God.

Additionally, in ancient cultures, gemstones were often associated with varying celestial powers and deities. Interestingly, they weren't merely ornamental; various civilizations believed they had direct influence over one's fate. So, when the names were engraved on these stones, it signified not just an identity for each tribe but also a shared destinable weight, something that connected the divine provision of God with each specific tribe in Israel.

This practice resonates across a range of religious and spiritual beliefs where names, stones, and spiritual representation hold cues to identity and connection. So much can be uncovered about tribal Israel in these intricate details about their worship practices. The echoes of this theme can be found in various traditions where names and history converge to deliver divine significance.