Perhaps the trailer revealed it.
The Dwarven realm of Khazad-dûm was first revealed to audiences in The Lord of the Rings: The Rings of Power episode 2. Hundreds of years before it was completely destroyed in the Third Age, the lush home of the Dwarves is seen in all its splendour.
Elrond faked his way inside the house in an effort to persuade Durin IV, an old acquaintance, to assist him with Celebrimbor’s new schemes. The Elven smith wants to construct a tower that will be able to hold a powerful furnace, as we learnt earlier in the episode.
Later on, however, viewers learn that the Dwarves are concealing something from the Elven kingdom. Durin IV finds his father in Khazad-depths dûm’s after being persuaded by an old acquaintance. Elrond “doesn’t know” their secret, he claims to King Durin III, but the king isn’t so sure.
The specific information they are concealing is not made clear in the moment. But when they get closer to a curious box, it opens and something shines inside. As King Durin III lifts something, the camera cuts away, and we hear a faint tinkling.
Even though the show has not yet revealed what is inside the chest, a well-known notion contends that it could be the priceless metal Mithril. In one of the promos for The Rings of Power, some keen-eyed fans spotted Durin IV was grasping a little bit of metal. It appears to be mithril, a metal that the dwarves in Khazad-dûm mined since it is lightweight and exceedingly powerful.
It was mostly used for jewellery and armour; in The Hobbit, Bilbo steals a chainmail shirt from Smaug. Nenya, an Elven ring that Celebrimbor makes and that Galadriel later tends to, was also made with it.
Due to its unique characteristics, Mithril had been overmined by the Dwarves by the Third Age, making it extremely uncommon. Therefore, it is entirely plausible that The Rings of Power are laying the groundwork for how this came to be and explaining why they are so guarded about their recent finding.
Even though Mithril seems to be the most likely choice, other viewers have speculated that the box might contain something completely different. Another observer speculated it might be the Arkenstone, a gem with its own inner light, in a post on Reddit(opens in new tab). Although the box glows, J.R.R. Tolkien’s lore would need to be altered since the jewel is supposed to be found beneath the Lonely Mountain hundreds of years in the future.
Another hypothesis holds that it might be the Silmaril, which got separated from Middle-earth. The Years of the Trees saw the creation of the Silmarils, which were Jewels of Fanor. They are highly prized by the Elves because of their connection to elf heritage, which may help to explain why King Durin III is so concerned that Elrond knows they have it.
But if that were the case, The Rings of Power’s authors would probably need approval from the Tolkien estate because inserting it at this time would be a significant alteration to the mythology. Additionally, since Amazon Studios does not own the rights to Tolkien’s The Silmarillion, they would need to be extremely cautious while developing the plot.
Find out more about The Rings of Power here. We’ve delved deeply into the world’s characters and examined several hypotheses regarding who is portraying Sauron and The Stranger’s identity. Check out our The Rings of Power release schedule as well to ensure you never miss an episode.