ΔE 14.8, fair: the same colour family, but not a straight swap. Terminatus Stone is noticeably darker, warmer than Ivory.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Terminatus Stone is noticeably darker, warmer than Ivory.
The same difference applies the other way round: Ivory is noticeably lighter, cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Ivory on the colour wheel See Terminatus Stone on the colour wheel
All matches: Ivory equivalents · Terminatus Stone equivalents