*Takes a deep breath* *Tries not to write a lot* *Writes a lot anyway*

I think it was both. Added for effect for the movie but also, their eye color IS enhanced with the Dark Gift. Here look at Louis’s pretty eyes change color:

First moments as a new vampire would be intense, Vampiring has just been installed into the system and director Neil Jordan probably wanted to make it very clear to the audience that this moment is as significant a moment as birth, and other than seeing the blood dry up and absorb into his face, and now we see the blue veins more prominently, it’s the eyes that really convince us that a change is happening. The eyes are the window to the soul!

In VC, it’s often noted explained at enormous length and exquisitely vivid detail how beautiful Louis’ emerald green eyes are *u* Both before and after turning. 

Short answer is, in canon, the Blood enhances what you already have. The amount of that enhancement varies.

~Hit the jump for 3 Shades of Lestat’s eye color.~

Movie!IWTV does not align with book!IWTV on eye color. It isn’t mentioned in the books that their eye color changes by a particular tonal measurement; the Dark Gift is different for each of them, but what it does do consistently is enhance what the fledgling already had as a mortal. 

For example, Armand has warm brown eyes as a mortal, IIRC, and they take on a golden (or amber) glow when he is turned.

Their eyes brighten and darken at different times in the movie, maybe it’s related to the intensity of their emotional state. I know for a fact that they all (main adult cast, not Claudia or Denis) had at least two shades of contacts in their color: a normal set and a brighter set and of course there may have been times, as with Orlando Bloom in LOTR, that someone forgot to put the contacts in before shooting, that’s human error. 

3 Shades of Lestat’s eye color:

Chastising your idiot child who could’ve finished you both would be intense:

Finding out that your daughter has polluted her own bed, less intense or intense in a different way? i mean it’s HER bed after all you don’t sleep with her thank goodness:

Pleased with self for A+ parenting, low intensity: