Vintage Smooth Glass Amplifier Jewel Lens, RED, Fits Fender and Other Amplifiers

I picked up a handful of these about 30 years ago from an electronics surplus store that had a lot of old equipment from the 1950s through the 1970s. This amp jewel has a smooth round top - not faceted like modern ones. It has a frosted base, which gives a unique appearance when lite. It has a lava-like appearance.  It is in excellent, used condition. 

Thanks for looking. Please ask all questions before buying.