Smelted quartz crystal is neither quartz or crystal?
You can look it up in the Wikipedia or World Dictionary.
“Smelting is a heat treatment for separating metals from their ores. The ore, often with other ingredients, is heated in a furnace to remove non-metallic constituents. The metal produced is later purified.”
In the smelted quartz, it is my understanding that when adding raw materials such as manganese (Mn) the result will be violet crystal, adding cobalt (Co) will be blue crystal, add chromium (Cr) for green crystal, adding selenium (Se) for the red crystal, add the liquid gold for the gold ruby color crystal, add doped (Er) compared with rose-colored crystal, adding cerium (Ce) yellow crystal, add neodymium (Nd) for light purple crystals. Quartz is in such abundance in China and labor so cheap that they can afford to melt down the crystal, remove all the impurities and add color as they see fit. I mostly find clear crystal infused with red since the Chinese believe that red is a color for prosperity.
The bubbles are from the air trapped in the crystal when it hardened. It brought me a lot of pleasure without breaking the bank.
I got some information from;
Fakes & Frauds : Smelt Quartz?.
I found the writers were ethnically disparaging, who am I to judge. But, I shall not use it again.