Rubylith is a brand of masking film, invented and trademarked by the Ulano Corporation. Today the brand has become genericized to the point that it has become synonymous with all coloured masking film
Founders of Intel inc. (Andy Grove, Robert Noyce and Gordon Moore) standing next to a Rubylith with a cutout for the Intel 8080A microprocessor, 1978.
A technician makes small-detail corrections of a circuit image on a large Rubylith. The image will be copied, miniaturized, and utilized in making computer chips.