ΔE 17.3, loose: different enough that you should pick on purpose. IJN Gray Green Nakajima is a little lighter, much more muted, warmer than Hydra Turquoise.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). IJN Gray Green Nakajima is a little lighter, much more muted, warmer than Hydra Turquoise.
The same difference applies the other way round: Hydra Turquoise is a little darker, much more saturated, 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 Hydra Turquoise on the colour wheel See IJN Gray Green Nakajima on the colour wheel
All matches: Hydra Turquoise equivalents · IJN Gray Green Nakajima equivalents