ΔE 25.4, loose: different enough that you should pick on purpose. Sapphire Gem is a little darker, much more saturated, cooler than Lavender.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Sapphire Gem is a little darker, much more saturated, cooler than Lavender.
The same difference applies the other way round: Lavender is a little lighter, much more muted, 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.
See Lavender on the colour wheel See Sapphire Gem on the colour wheel
All matches: Lavender equivalents · Sapphire Gem equivalents