Cosmic Talisman Basics

[Ydex]

All things being equal--same effect, same stat boosts-- what is the scale from top to bottom?
T1 White through Red, then T2 White through Red, then T3 White through Red?
Or T1 White through [???] overlapping with T2 [???] through [???]

I'm asking because in my inventory I have a Purple T1 that is nearly identical to a White T2. Do the Tiers overlap starting at Purple ???

Or when they say "random" is it truly, completely abstractly illogically random?


P.O.S. System