Very nice! Do they ripen to red -- I think thats the typical transition. Should get more complex and maybe even touch of initial sweetness in flavor. (Generally speaking -- have never tried Purple Tiger before)
...maybe try pickling in vinegar -- might retain the purple/violet-red color?
Oooh now I'm curious! I currently have Bolivian Rainbow which starts purple, then ivory, then orange, then red. Also have a black -- I think Czech. black -- I'm going to try pickling in acid like vinegar and in alkaline by pre-soaking in pickling lime. Would the lime make them blue?