Grave Robber vs Sterling Silver

How close are they?

ΔE 15.6, loose: different enough that you should pick on purpose. Sterling Silver is a little darker, much more muted than Grave Robber.

Can I use Sterling Silver instead of Grave Robber?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Sterling Silver is a little darker, much more muted than Grave Robber.

Can I use Grave Robber instead of Sterling Silver?

The same difference applies the other way round: Grave Robber is a little lighter, 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.