How to convincingly add color to jet black eyes

Question

Where I'm from, a large fraction of the population have jet/pitch black eyes with no "texture" to them, or a very dark brown.

In cosplay photography (my field), models would simulate colorful eyes of the fictional characters they're cosplaying by wearing colorful contacts. But for various reasons, sometimes they cannot wear contacts on some shoots (e.g. eyes are really irritated that day). And a popular request is that they would like me to edit the eye color in to post to make it look like they're wearing color contacts.

I have looked for online tutorials on how to change eye color: however, I could only find tutorials about changing eye colors when the eye already has a color - presumably, written by and for a western audience where there is a large diversity of eye colors. The tutorials usually outline the same technique (from my understanding): lasso the eyes, create a HSL adjustment layer, and adjust the hue.

If I understand correctly, this method does not seem to work for pure black eyes, because hue-shifting black by any degree still gives you black. Using the "colorize" option helps a little, but without the "texture" (the blood vessels radiating outwards from the pupil), the eye looks like a solid color.

Below is my attempt, working on the model's right eye and leaving the other eye untouched for comparision. Instead of adjusting HSL, I used the blue tone curve instead. I see 3 main issues I need to solve:

1. Just colorizing the eye area directly will result in a solid color. The white streaks (blood vessels?) that extend radially outwards from the pupil are missing in dark eyes, I solved this by downloading brushes online meant for painting in irises in digital art.
2. From my knowledge, the catchlights (or the reflection of the scene in the eye) should keep their original color (pure-white ish), but the adjustment layer would indiscriminately color everything within the eye.
3. Lassoing the eye will include the pupil in the center (causing it to also be colored). From the best of my understanding, the pupil should be black regardless of iris color. I solved this by painting a black dot in the adjustment layer's layer mask but surely there must be a more elegant solution.

For reference, here is a photo of another model wearing actual color contacts in similar lighting conditions:

Is my attempt "good enough", or is there a more convincing way to do this in Photoshop?

Addendum: by "eye color" i am specifically referring to the iris, not the eye whites

Answer 1

The problem is not coloring the eye, the most important thing is to extract the shadows and mid-tones from the iris. In lighter eyes, the difference between the color of the iris and the pupil is clearly distinguishable, but not in dark eyes since they have the same tonal value. In the example below, prior to coloring the eye, there is a step to extract the mid-tones with levels.

Working on the right eye:

After making the eye selection, on a levels adjustment layer, move the mid-tones to the left to lighten them and the shadows to the right to differentiate shadows and mid-tones:

Smooth the mask with a Gaussian blur:

Add a color fill layer using the same mask with the chosen color and change the layer blend mode to Color:

Answer 2

This question spurred me to wondering.

WARNING, Photographic Heresy to follow:

I've recently been experimenting with using Stable Diffusion AI and photography. My first experiment was to take an old badly damaged photograph and attempt to us AI to repair severe damage that included half an eye missing entirely.

This brings me to my second experiment, "This question and image".

Stable Diffusion AI is very computer intensive. So I took a crop of the models left eye to work with, and ultimately merged the result back into the original image.

Original

Original image EyeCrop

Next I masked the iris for Inpainting. Mask Iris

I then generated many experimental runs. Here are 6 that I 100% overlayed back onto the original.

Turquoise

Blue

Green

Emerald Green

Yellow

RED

It's very easy to radically deviate from the reference image and end up with something unrelated. Used judiciously I believe we will see AI leveraged in a similar manner to Photoshop. Where's the line? I don't know!