Doublet, but why?

Hi Everyone,

The attached stone came in for new setting. Hadn’t given it much more than a quick look until today, as I originally assumed it was an amethyst. Top facets are worn down as I would expect. Was told this was possibly from the late 60’s or 70’s

As pictures it is obviously some type of doublet.
From top a light purple with a flash of pink.
From back a darker purple with blu flash around edge.
Chelsea filter shows red / orange.
Short wave give a blue white glow.
Long wave goes red.

Any thoughts on this ? What were they trying to simulate ?


Additional pics

Hello Friend! Very interesting … I came across a similar thing several times in the work and it was really doublets - imitation of amethyst - quartz + glass and just in the 60-70s of the 20th century, they did it sometimes.
Did Amethyst not check for inclusions? because inclusions can tell a lot, especially inclusions in quartz, and they are very characteristic of both natural and imitation.

And try to put it in water and take a picture in the water, or just describe what you see