It is actually a huge red flag when people list their goldstone or opalite pieces as "natural." These are glass gemstones, completely man-made, and anyone trying to sell them as a "natural" stone is either lying to customers or doesn't know enough about how their own products are being sourced and produced.
I was once in a tourist trap adjacent rock shop and spotted some little pieces of very pretty blue aventurine (goldstone) glass. (There is also a natural rock called aventurine. That's an entirely different thing.) By sheer coincidence I had been reading about the history and production of aventurine recently, so I excitedly picked up a piece and started telling my friend about it. It's cool stuff! Metal oxides are mixed into the glass at extremely high temperatures, then kept in a low oxygen environment, allowing tiny crystals of metal to precipitate out throughout the glass. The type of oxide determines the color. Copper makes the golden-reddish classic goldstone, while cobalt, manganese, and chromium make blue, purple, and green. (The latter three are all typically extremely dark, and "blue" aventurine often looks like an incredibly deep black.) Though the process we know was invented in Venice in the 17th century, examples of aventurine dating back as far as the 13th or 12th have been found in Persia, where it was apparently used to make Islamic prayer/protection amulets.
Anyway I'm in the middle of yammering about this when I realize the woman at the checkout counter, who I believe also owns the place, is glaring daggers at me. I am autistic. I am not good at noticing or correctly identifying death glares. This was obvious enough for me to pick up. I falter to an awkward stop, midsentence, and there is a moment of dead silence.
Then she snaps, "well the copper is natural. It has the natural properties of copper."
(Again, it was blue, so it actually had "the natural properties" of cobalt, whatever that means. Mostly it is glass, and has the properties of glass.)
I wasn't insulting the aventurine! I was being very enthusiastic about it! If anything I was doing an impromptu sales pitch, pointing out how the irregularly distributed glittering crystals in the blue-black glass created a sense of depth that made it look like stars in a low-light night sky, talking about how difficult it is to make and what an interesting history it has! But she was so mad.
Aside from being kinda scummy, it's just sad. Aventurine glass is such a cool material, and it's beautiful. People should be able to appreciate it for what it is.
