Thanks chaps. A few fraught moments along the way but got there in the end.

Yes camel bone (Anyone want to buy 99.995% of the rest of the camel? Going cheap? ).

It's supposed to be a harder bone than the typical cow bone you get. More like ivory. Quite yellow/orange in colour but it goes with the amber tint. (Also it was the only nut of the right thickness and depth I could find on Amazon at the time unless I wanted to make one from a blank. But I'm quite impressed.

There are over a million wild camels in Australia, originally brought over by the Brits in the 19th century from India and Afghanistan for use as transport in the dry interior. And they are a big nuisance, so are being culled. So it may well be Australian camel bone.