What are they, and what purpose do they serve?
-History and facts about Black Mirrors
In terms of history, black mirrors were made of polished obsidian glass (volcanic rock), and were first brought back by Hernando Cortés in 1530 after his conquest of Mexico. The Aztec priests used them to conjure visions and make prophesies of the future. Obsidian mirrors were used ritually to spiritually access the Aztec underworld and communicate with the realm of the dead. They were said to be used for a ruler to see the future, and for others to see themselves look back at them.
Later, John Dee, with the help of a psychic-medium (and convicted criminal) Edward Kelley, had conversations and visions of angels in the mirror’s reflective surface, creating what is known as the "Ennochian" language, said to be the precursor to ancient Hebrew, and the language that God used to speak to Adam. These angels (or perhaps demons) requested certain real-world things happen, in payment for the information they imparted. These acts and requests became more and more deprived towards the end of Dee's experimentation.
This is very occult, with little known about what, if anything, was found to be true. Dee believed that this practice would result in the the beings/angels contacted through the mirror, having knowledge that would aid the English in the domination of the known (and at that time, unknown world). Essentially, he sought information that he could use to guide the future. Interestingly, Dee has since been suggested to be a spy for Queen Elizabeth I, and part of the original MI5, and signed his letters with the signature '007'.
Dee would eventually force Kelley to stare into the mirror for long 'scrying' sessions, pushing him to the edge of madness, if not deep into the territory of it.
In summary, black mirrors are said to be a tool of prophesy, but if one looks too hard into them, for too long, madness awaits, and the looker may be consumed by their visions of the possible. In this respect, it may be argued that a black mirror is nothing but the reflection of one's soul in that, it is what the soul wants without heeding any danger (or listening too closely without caution) towards something fundamentally uncertain, and will likely result in a terrible state of reality for them. They spring forth warnings of what may be, possibly even will be.
-Alexandre makes custom black mirrors and sells them on his online stores. You can find them on his Etsy store, or contact him for custom orders.
-Each black mirror in stock is unique, and the sizes vary. They range from table top sizes, to large frames you hang on the walls.