When it comes to autograph investments, the criteria for value is simple: the more historically important the signed document, and more legendary the signer, the better.
With this in mind, it's unsurprising that when we asked Bobby Livingston, Head of Public Relations at RR Auction, to name a highlight from his job, he mentioned "opening a box and seeing a letter from Thomas Edison talking about the phonograph."
Signers of historic importance don't come much more important than Edison (indeed, if it wasn't for him, you wouldn't be reading this article online right now).
From the phonograph and the battery to the light bulb and beyond, the legacy of Edison's achievements can be found everywhere in today's multimedia society.
What's more, for collectors Thomas Alva Edison is a gift that keeps on giving. In life, Edison was a multimedia pioneer who changed the course of human development - and, even in death, he's still able to throw up a few surprises.
The latest of these are a series of pioneering videos, shot by Edison with his assistant, William Kennedy Laurie Dickson, from 1888. The clips have been newly-available to the public by the US Library of Congress, and you can watch some of our selected highlights above.
The videos are held in the Library of Congress alongside rare and historic photographs and documents - but what sort of values to these items sell for on the collectibles markets?
Well, while Bobby Livingston had a chance to see a letter from Edison talking about the phonograph, another collector had a chance to own an original drawing of his most famous invention: the lamp.
Scrawled in Edison's personal notepad prior to the patenting of his lamp in 1880, the personal sketch of great historical importance sold for $7,000 at Max Rambod Inc in 2008.
Elsewhere, rather than having a chance to own one of Edison's ideas, collectors had a chance to own a pair of the spectacles through which he realised them.
A pair of reading glasses were acquired in 1971 from curators of the Edison Collection(which was housed in the home of one of the famous inventor's sons, Charles, the former governor of New Jersey) was sold by Guernsey's for $5,500, also in 2008.
And valuable Edison autographs don't just have to be on historically important documents. Another signatures, this time on a black and white photograph of the inventor shown standing with his hands in his pockets, brought $3,750at a 2004 auction held by Hantman's.
The 1904 signed picture also bore the inscription: "To My Friend Marks Pioneer of the Early Days of Electric Lighting, Thomas A. Edison, April 26, 1906."
What's more, considering that each of these collectors are likely to gain value in future years, it appears that Edison's collectibles - and his legacy - will continue to burn as brightly as his patented lamp.
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