Eye of Horus
A massive blue sapphire, and a powerful warding artifact
The Eye of Horus, when properly attuned, functions as a nearly impenetrable ward against remote scrying over the place or people it is attuned to.
The exact nature of its workings – such as if it can be overcome – are not known.
Somewhere around 3100 BCE, early during the First Dynasty of Egyptian pharaohs, an ancient cabal of magicians gathered in secret at the sun temple located in the Egyptian city of Abedju, better
known by its Greek name, Abydos. At the sun temple, the mages gathered their collective powers and created (or, as some rumors suggest, unearthed) two artifacts of great power, known thereafter as the Eye of Horus, and the Abedju Cipher.
The cabal arranged to have the artifacts added to the regalia of the first recognized pharaoh, Narmer. As part of that trove of riches, they were entombed with Narmer after he died. There the Eye of Horus remained for some many centuries, until it is believed to have been stolen by Roman thieves and carried into the Italian peninsula.
There it remained for many years more, passing from hand to hand and family to family over the years, until it was finally recovered by The New York City Mage Mark Vandross in 2005 in an old mausoleum outside of Naples.