whelk type --don't think they are dakshinavarti shank conch

[Shells85]

Thank you in advance for helping me identify these four shells.
I did find a lot of information about how whelk shells are confused with Dakshinavarti shankha conch shells which are quite valuable.
My research said that the conch shank has 3 to 7 ridges on the conlumnella. Am I correct that my 4 shells do not have these ridges ?
My guess is they are whelk shells but I can not figure out what type of whelk--Lighning, channel or knobby.
The blue shell looks different to me.
Are the blue and white shells more valuable than the white/brown ones

[paul monfils]

The shell on the left in the first three pictures is Busycon carica. All the others are Busycon contrarium.

[Shells85]

Thank you for taking the time to identify my shells.