Should I save my purple "planarite" for the next zone?

I see that in King's Retreat there is a Rare Planarite Goods vendor. I can afford the purple pants, it would use up my only purple 'planarite' (forgot what it was called, received from an invasion). Would it be better to just save it for the next zone?

Currently level 17.


Each zone has its own kind of Sourceshard/Sourcestone (blue/purple-quality stones). You'll be unable to use your Corrupted Sourcestone (the purple stone you speak of) in Stonefield, for example.