Holographic Paint vs Old Gold

How close are they?

ΔE 24.0, loose: different enough that you should pick on purpose. Old Gold is noticeably darker, much more saturated than Holographic Paint.

Can I use Old Gold instead of Holographic Paint?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Old Gold is noticeably darker, much more saturated than Holographic Paint.

Can I use Holographic Paint instead of Old Gold?

The same difference applies the other way round: Holographic Paint is noticeably lighter, much more muted.

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.