Very Interesting. I’ve been tempted to do the same but the cutting scared me away. How did you cut it?
Diamond saw. Very carefully. I wanted to cut the end off because it was badly chipped. So it made a perfect test subject.
The carbide blade in the hack saw would do it but I'd still be cutting it and I think I'd need a new blade and a new arm too.
We know Trans Arks come in 'colors' - some are known to be 'yellowish'. General speculation and word of mouth from sellers say that the greater number of trans arks that were sold were white. I suspect that a great number of yellowish Arks were not yellow to begin with. Possibly through oxidation and use with oil they were, for lack of a better term, tinted. Oil definitely seems to shift the coloring to the warm end of the spectrum. A stone that already has a 'warm tone' would be pushed further into that hue with some oil added in. Oddly, I see that one does not need amber-colored oil to get the diffraction going in that direction, crystal clear oil will do it. So there is more to this puzzle that what meets the eye. Remember, part of the reason the white stones are white is due, in part, to light diffracting off the tiny bit of water in the stone. Perhaps just from losing moisture their colors shift. Indians used to change the lustre by treating the stone with heat... there are many possibilities to consider.
I don't know that I'd agree with soaking a very dense Ark in anything is a sure fire way to remove every bit of seeped in oil... these stones are dense, very very dense and I can see how IF there is oil that took 80-90 years to creep into it, then I can see how it would be possible for it to not always be 100% removed with a short term bath. I had this one wrapped up in a clean paper towel for a verrrry long time in a very warm area, and zero oil crept out onto the towel - so that's telling. I've actually used SG to clean up some old oil stones and it is not always a 100% perfect 'solution' (small pun) to getting the oil out. I am fairly convinced that if I soak the cut off piece in SG for a good long while that it would seem to clean up a bit, but I also feel that the coloring would be shifting toward warm shortly afterwards.
I don't believe that all of this is all that complex. It's just that we do not have all the parts of the puzzle on the table; we weren't there 100 yr ago when the stone was first cut. We just show up 100 yr later and start guessing.