ΔE 16.1, loose: different enough that you should pick on purpose. Ivory Light is a little lighter, much more muted than Quartz Skin.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Ivory Light is a little lighter, much more muted than Quartz Skin.
The same difference applies the other way round: Quartz Skin is a little darker, much more saturated.
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 Quartz Skin on the colour wheel See Ivory Light on the colour wheel
All matches: Quartz Skin equivalents · Ivory Light equivalents