These have been probably posted previously but they belong in this thread. The Indigo is a bluer bird overall than a Turquoise, especially in the face and the front of the bird. The df Indigo is a lot greener as would be expected knowing that with the second factor, these Parblues have more psitticin than the sf Parblue. The flights of a df Indigo are darker however the image below does mis-represent them. They are not that dark.
Indigo

Indigo

Indigo and df Indigo
I often wonder if the name indigo is the correct name for this mutation as a lot of breeders here in Australia have jumped in saying they have an indigo because the bird is lightly pasteled.
As many have jumped in claiming they have 'Sapphires' just on the appearance, totally forgetting what they bred them from. Let's not fill this thread with argument and supposition based only on the sf Indigos. The sf Parblues can overlap in appearance, the df Parblues have been shown to have demonstrably different phenotypes to their df co-alleles. Breed them together people and treat them as distinctive recessive mutations to get the df Indigo and in combinations on the perch in your aviaries. There is no mistaking on that basis. Do not breed Indigos to Turquoise or Emerald, the phenotypes will be in- between in phenotype and like hybrids will get lost and mess up yours or someone else's breeding.