Gambler's Cheater Glasses. These glasses are the rarest of the rare as they are not completely blue, but have blue shaded area at the very top of the magnification power glasses. Unfortunately the left lens has been cracked. Perhaps the crack was caused when this gambler won too many times. Blue-tinted spectacles enabled the wearer to detect marks made on the backs of cards with phosphorescent ink, which was invisible to the unaided eyes of his opponent".
In K. C. Card Co. Blue Book Number 436, page 22 there is a listing for Luminous Readers. The book states "Luminous Readers originated and introduced by us have been successfully used in all parts of the country. These cards do not bear any visible mark, but when viewed with our Luminous Visor or our Luminous Glasses the work appears as plain as the figure 8 on the back of the card pictured". Just below this listing is a listing for the Glasses. I am including a glasses case made of paper mache' covered with leather, made to accommodate straight temples, circa 1870.
"Never gamble with a man who knows both sides of the cards."