Indigo to crystal?

With the help of you guys on here and looking at many, many websites on the subject, I'm starting to understand the indigo thing but what I really don't comprehend yet is the crystal bit?

I've done a test on www.auracolors.com and score highly on indigo and violet but low on crystal, so I guess I'm not one (yet?). Can anyone explain the differences between indigo and crystal please? Is becoming crystal an automatic thing when one starts to understand the indigo phenomena?

Any thoughts much appreciated!