G'day Alan,
I presume it probably started by a westerner recently. In my case, I stumbled upon the pic that Detlef had shown us earlier in this thread and I googled hippo ivory to see the possibility and I think it is possible that it is hippo since I didn't found anything else that matches the dotted criteria.
I did wondered how hippo ivory arrived here and the possibility that the people at that time "disguise" it as the cool sounding gigi ikan instead of the ugly hippo's tooth (assuming that people at that time know what is a hippo and have a common perception think that it is ugly and unclean) due to marketability and the cleanliness issue, but I never pursued the quest any further and I won't be able to defend my "theory" above.