link to 1983 Audio review of original SOTA Sapphire
It mentions the Sumiko Gem also, but not the back story I remember. My understanding is that the Gem design was a prototype for most of the ideas incorporated later in the Sapphire, including the inverted sapphire bearing. It was pitched to Sumiko, who added it to their product line. I don't know if Sumiko, SOTA, or a pre-SOTA company manufactured the Gem. The above story suggests that Fletcher et al formed a company to build the Gem. It may have started under a different name, but at some point became SOTA. SOTA has changed hands a few times over the yeas, but would be worth contacting to see if they can answer your questions.
After seeing how the Gem worked in the marketplace, the more refined Sapphire came into being and was sold direct from SOTA.