Patagon Pine vs Light Turquois (Phthalo)

How close are they?

ΔE 15.1, loose: different enough that you should pick on purpose. Light Turquois (Phthalo) is a little darker, more saturated, cooler than Patagon Pine.

Can I use Light Turquois (Phthalo) instead of Patagon Pine?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Light Turquois (Phthalo) is a little darker, more saturated, cooler than Patagon Pine.

Can I use Patagon Pine instead of Light Turquois (Phthalo)?

The same difference applies the other way round: Patagon Pine is a little lighter, more muted, warmer.

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.