Dominant to Tonkinese - Lilac Tortie
Ivory is pure the following pedigrees prove this
Tank Hides Zias hidden fur
Seth also hides Zias hidden fur
We know Tank and Seth both hide Zias hidden fur because Abyssinian - Lilac is dominant to both of their shown furs which come from their fathers.
Tank & Seth bred together and produced Justine & Kevinn. These are Both Tonkinese - Lilac Torties, since this must be the hidden fur of Tank & Seth and they have the same hidden fur from Zia that means Justine & Kevinn are pure Tonkinese - Lilac Torties as are all of their offspring, which brings us to Ivory a pure Tonkinese - Lilac Tortie.
Therefore if Ivory is pure then she couldn't pass anything else under the Tiger! - Dusky Green when she bred with Roger meaning that Tiger! - Dusky Green is dominant to Tonkinese - Lilac Tortie.