When I first saw the cert, there was no feather. Yet, I saw feathers on the images.Then I realised that this is the feathers that don't break the surface, hence labelled crystal. Since this is the first time I'm seeing it, I thought I'd share it.
http://www.jamesallen.com/loose-diamonds/round-cut/1.01-carat-h-color-vs1-clarity-excellent-cut-sku-620524
http://www.jamesallen.com/loose-diamonds/round-cut/1.01-carat-h-color-vs1-clarity-excellent-cut-sku-620524