Petroleum Brown vs UK Light Stone

How close are they?

ΔE 21.2, loose: different enough that you should pick on purpose. UK Light Stone is noticeably lighter, more muted, cooler than Petroleum Brown.

Can I use UK Light Stone instead of Petroleum Brown?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). UK Light Stone is noticeably lighter, more muted, cooler than Petroleum Brown.

Can I use Petroleum Brown instead of UK Light Stone?

The same difference applies the other way round: Petroleum Brown is noticeably darker, more saturated, 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.