FWIW, Richard Helmstetter had ivory at his factory in Iruma, Japan back in the early 80s, but I never saw it in any of his cues.
I lived in Japan then and had a Richard Black custom that had a cracked ivory ferrule, so I called Richard to arrange a repair. He told me not to ship it back and to take it to Helmstetter and he gave me his phone number. I called him and he gave me directions to the Adam factory and I went there, met him, and had a tour while a new ivory ferrule was put on my Richard Black shaft.
He offered to front me dozens of cues to sell on the military bases, but not many military people were that into pool.
I wish I had bought a dozen and kept them. He was giving them to me at almost the cost of building them.