Eye glasses have been around in various forms since before Christ(BC). In the 19th century we saw some development in spectacles and by the end of the century they were becoming more common place and designer fashionable. I stumbled on a book "Spectacles and Eyeglasses" by Richard Jones Phillips ©1895 that goes into the process of making eyeglasses. Below is an excerpt about the type of materials used to make these spectacles, I thought it fitting when writing about our characters putting on spectacles we know some of these little tidbits. Also there are some great photographs and illustrations in the book.
The Material of Spectacle Frames is usually gold, silver, or steel. Various alloys have also been employed, and sold as aluminium or nickel. So far as I have examined them, they consist principally of tin, and contain little or none of the metals whose names they borrow. Real nickel is too flexible a metal to be used with advantage for spectacle frames, while, so far, no means have been found of soldering aluminium firmly. Were this difficulty overcome, the lightness, stiffness, and freedom from rust of aluminium would make it an excellent material for cheap frames. Silver, like nickel, is too flexible, except for workmen's protective goggles, or some such purpose, where very heavy frames are allowable. Gold, of from 10 to 14 karat, is, by far, the best material for frames. Finer than this it is too flexible, while if less pure it may blacken the skin. In the end, such frames are cheaper than steel, as, owing to the liability of the latter metal to rust when in contact with the moist skin, the gold will outlast it many times over. In eyeglasses, however, the parts are heavier, and the metal is not in contact with the skin; so that there is not the same liability to rust. The gold frames furnished by opticians in this country usually have a stamp mark on the inner side of the right temple, near the hinge, which denotes the fineness of the gold: thus 8 karat is marked -(-; 10 karat, B. 12 karat, *; while 14 karat, or finer, is marked 14k, etc.