THE HEBREW UNIVERSITY OF JERUSALEM:
Impression of King Hezekiah’s Royal Seal Discovered in Ophel Excavations South of Temple Mount in Jerusalem.
First seal impression of an Israelite or Judean king ever exposed in situ in a scientific archaeological excavation
Discovery brings to life the Biblical narratives about King Hezekiah and the activity conducted during his lifetime in Jerusalem's 1st Temple Period Royal Quarter
This is an exciting discovery, chiefly because, as it says above, this is the first seal impression mentioning Hezekiah which has been uncovered in a scientific excavation. Other Hezekiah bullae (clay seal impressions) have surfaced on the antiquities market since the 1990s, but one could always doubt their authenticity. There is no doubt that this one is authentic. It is very sad that the papyrus document it once sealed has long ago disintegrated into dust.
For more on the earlier Hezekiah bullae, including a damaged one published by Nahman Avigad in the 1980s without his recognizing the name on it, see this 2002
Biblical Archaeology Review article by Robert Deutsch:
Lasting Impressions: New bullae reveal Egyptian-style emblems on Judah’s royal seals. (The latter was brought to my attention by Antonio Lombatti.)
UPDATE: It sounds as though the question of the bulla being "exposed in situ in a scientific archaeological excavation" may require some qualification. Candida Moss notes the following in her Daily Beast essay
Archaeologist Says the Bible’s King Hezekiah Is Real:
But Robert Cargill, an archeologist at the University of Iowa, told me that the claims about biblical proof are overstated. “If this is a legitimate object, then it simply confirms the existence of a king named Hezekiah in Jerusalem.” That, Cargill added, is something scholars already knew from other archeological discoveries.
The story has made headlines in the British tabloids, but archeologists like Cargill are more skeptical both about the evidence itself and the potential agenda of the find. The significance of the discovery hinges on the claim that it was uncovered in its original archeological context, but the area in which it was unearthed is politically contested and archeologically compromised. The material is being sifted from piles of dirt removed as part of Palestinian construction in the area. As such, Cargill said, “there’s no reason to believe that it is a forged object. The problem lies in the compromised archeological stratigraphy at the point of discovery.”
If this is accurate, the bulla comes from the salvage archaeology of a construction site and the dirt was removed as part of the construction, rather than, apparently, by the archaeologists. As Professor Cargill says, there's no reason to think the object is forged, but this is not quite the same as it being scientifically excavated in a stratigraphically rigorous archaeological excavation.
UPDATE: Professor Cargill points me to
this, which indicates that the Temple Mount Sifting Project actually found the object in 2010. It remains unclear from the current reports whether the dirt came from construction excavation or scientific, stratigraphic, archaeological excavation.
UPDATE: From the Hebrew University press release:
This bulla came to light, together with many pottery sherds and other finds such as figurines and seals, in Area A of the excavations (2009 season), supervised by Hagai Cohen-Klonymus.
But apparently the dirt was not sifted until 2010.
ANOTHER UPDATE: Yes, it was a garbage pit. What does that mean? Was it garbage from a specific period in a clear stratigraphic context? Sounds like it, in which case I would count that as excavated in a stratigraphically rigorous archaeological excavation. But I am not an archaeologist and am not going to try to comment on the fine points of stratigraphy. I assume the details will be made clear in the publications. Meanwhile, it's an interesting object whose genuineness is beyond reasonable doubt. It confirms what we already knew from
the Sennacherib Prism etc., that there was a king named Hezekiah around 700 BCE. It also identifies Ahaz as his father, who is also mentioned as such in the previously published bullae. Any doubts (but I don't know of any) of the genuineness of the latter bullae seem now assuaged. Ahaz is also known in his proper time from an
Assyrian inscription.