Polished Silver vs Quick Silver

How close are they?

ΔE 16.0, loose: different enough that you should pick on purpose. Quick Silver is noticeably lighter, more saturated than Polished Silver.

Can I use Quick Silver instead of Polished Silver?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Quick Silver is noticeably lighter, more saturated than Polished Silver.

Can I use Polished Silver instead of Quick Silver?

The same difference applies the other way round: Polished Silver is noticeably darker, 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.