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Figwit Lives!, it explains it all, I hope! I found it so amusing, I had to have Figwit as my picture (yep, that's Figwit!)
The ring was created by aliens as their first attempt at making intelligent life. Unfortunately, it tried to take over their planet and after many long battles, they managed to capture it, though half their population was wiped out as a result. The craftsman who had made the ring had forgotten to add the self-destruct button, so the aliens had no way of destroying the ring and instead threw it into space. After many long adventures, the ring hurtled to Middle Earth and was picked up by Sauron, who was a keen astronomer and wanted to study it.
What was the ring made of?