Here's the lav feather scans:

I don't know the technical terms, but what I mean for "outer view" of the feather is the external surface (ie where the sun does shine smile ). Yes, the darker iridescent lavender shade is mostly seen in the main tail & wing flight feathers (inner view, especially along the feather shaft). The pale feather shafts should be everywhere on the external surface, although there may be a few darker shafts on the breast, etc (but not main feathers).

It also works some on the phaeomelanin feathers:
Inner view of lav/lav tail feathers (extreme eumelanin restriction):

The same pullet (pale feather shafts):

It doesn't work on blue /lavender combination though. These have traits of both blue & lav. The eumelanin ground colour is usually a lavender shade, but the feather shafts are similar to Bl, ie darker shafts both external & inner views.
Eg, the following hen is lav/lav Bl/bl+ (lav Porcelaine with Bl/bl+ blue):

External view of lav/lav Bl/bl+ tail feathers:


Inner view of lav/lav Bl/bl+ tail feathers:

The following set of images, from top left to bottom right:

Top Left: Blue Buff Columbian (Blue only: Bl/bl+ Lav+/)
Top Right: Blue Lavender Buff Columbian (Bl/bl+ lav/lav)
Bottom Left: Porcelaine (lavender only: bl+/bl+ lav/lav)
Bottom Right: lavender feathers (lavender only: bl+/bl+ lav/lav).

The following hen is Blue only (Bl/bl+ Lav+/Lav+):