Color Options (Danbooru Eye Color Tags):

Amber, Aqua, Black, Blue, Brown/Hazel , Green, Grey, Orange, Pink, Purple, Red, White, Yellow

Usage:

After a lot of testing, I've found that the following example works about 75% of the time. The right and left eyes are from the subject's perspective, not the viewer.

Note: This LoRA and the trigger words should be at the very end of your prompt.

heterochromia - Triggers the effect
COLOR eyes - Call out each eye color
right eye COLOR - Right eye color
left eye COLOR - You get the idea...

Example:

<lora:Dark_Heterochromia_Pony_v0.2:0.5> heterochromia, COLOR1 eyes, right eye COLOR1, COLOR2 eyes, left eye COLOR2, <lora:Dark_Heterochromia_Pony_v0.2:0.5> heterochromia, amber eyes, right eye amber, aqua eyes, left eye aqua, <lora:Dark_Heterochromia_Pony_v0.2:0.5> heterochromia, purple eyes, right eye purple, pink eyes, left eye pink,

For the other 25%, you can recreate the image by using "BREAK, reversed". This seems to "fix" those images that get the coloring backwards. The image may not be exactly the same, but pretty dang close.