I'm no ambergris expert, but i know ambroxan and cetalox quite well. I was given some sample vials - one being of "white" ambergris oil from Agarscents after ordering some musks and forgot about that vial. Found it a few months ago (after a couple years storage) and the liquid had evaporated leaving behind the familiar white crystals (and smell) of ambroxan - unmistakable. Even compared it to my own bottle of ambroxan - exactly the same.
Left me feeling a bit suspicious about the quality and prices.