...and yet, you didn't even address my basic points in my last post.
Furthermore, your sheepish question of, "Could a gold ring sound different on a Deus 2 vs an equivalent ID reading piece of aluminum?", implies that you can. Yes, I would agree that can be done with any decent detector, provided that there is a specific size and piece of aluminum, a specific ring, and they are above ground in one of your controlled tests. Too bad metal detecting doesn't work that way. Once in the ground, there are various sizes and types of gold rings and aluminum trash, at different depths, and different orientations. All of which changes tonal response and TID. So much so, that it is an impossibility for an induction balance metal detector to distinguish between gold jewelry and aluminum trash in the wild.