I am with Steph here.
Bright colors were always in production, why not brighter?
This was no sham or mistake, it was well thought out and produced for this very reason.
The glass makers alway tought this out regardless of the final product being it a plate, cup, saucer---- or marble.
The light was not so electric when these colors were introduced. Imagine the colors under gas light or other types of light.
Expand your mind to the good old days🌞.
Marble--On!!