As long as it's solid color, the color will never change.
The so-called solid color is the natural color of glass. When different chemicals are added to the ingredients, the originally transparent colors will change into different colors, such as amber, soot, gray blue, olive green, lake blue, pink, orange, etc. This color, because it is the natural color of glass, will never change.
The solid color of the cup, there is a feature: thick material where the color is dark, thin material where the color is light.
The cup of solid color in the picture below is for reference.
