The coloring of each feather (including the shaft) should be absolutely uniform in a lavender. There should not be some feathers darker than others. Photos sometimes belie what you can only tell in person.
My avatar is a lavender cockerel at abou 4 1/2 months. His tail feathers APPEAR darker but they really aren't...it's just because there are a LOT of them in that area. The shaft of all of his feathers are uniform with no dark spots or a dark line down the shaft that is typical in blues and splashes.