attached image show the issue.

Does this rainbow effect happen on all armor or just this one?
Also what character class are you? (I'm assuming this is the level 1 starting equipment.)

I'm asking as someone who doesn't play classes that wear big clunky armor, but I'll see if can reproduce on my computer.

This appeared on the paladin class. Just started the game using a premade female paladin.

I've then created a new game with the female fighter class and that appears to be working correctly. I don't know if I've seen the same issue for now, I'm outside of the temple in the city hub.

One interesting question I have for you is why in the game with the paladin the long sword was valued at around 2.5 k gold, and in the fighter version is around 30 gold? Is this a roll value at the start of the game? In the paladin version I've found the sword in the cabinet in the first room and made 2.5k lol :D

I've made a new game using the female paladin and the issue is visible, but now I've found both on the character and in the drawer a longsword +3 that cost 10k :D

so my poor fighter going around with a common sword and barely putting together 200 golds to hire the thief, and the paladin has a +3 sword equipped and now 10k in her pockets :D

see screenshot :D

I guess it makes sense, she may be from a rich family

edit: this has no mods or anything, just the default install from gog.

WAIT. I've now noticed she has near 3k in her pockets from the start :D

I tried to reproduce your rainbow paladin and nada. Everything looks fine on my end. Maybe human paladins are just really colorful with their armor choices in your game?

The only thing that has me not suggesting that it is a video card related issue (meaning your video card is making the game misbehave) is that in this situation, it should happen regardless of the character class so long as you're using the same equipment. I'm going to say it probably depends on if you make a character elsewhere that has a few levels on them versus completely brand new character. I've noticed that while the weapon you find in the chest in the tutorial level is random, it does seem affected by the level of your character. The whole prelude section is one big tutorial technically, but you can play through it for flavor.

Alternately, maybe the game just doesn't like fighters as starting characters?

I typically play rogue/fighter if I'm going to do fighter anything, which means taking rogue first as the class has significantly more skill points so you always start with rogue and never fighter. What the....? Aren't paladins supposed to be above material wealth? Even my rogue has never had a weapon worth 10k waiting in the starting chest if brought in as a Level 1. I think you may have gotten extremely lucky there.

I've studied this mystery, sorry noob to this game, turns out in the premade characters list there are high level premade ones. I didn't notice that and I've assumed all of them starts at level 1.

maybe the game then scale up the enemies? I don't see the point of playing with this character if the enemy remain at low level. Or maybe this is a character for a different module that requires high level characters.

But because that paladin woman is high level, the weapons and the armour is magical, that is what the description is saying. so that wrong looking effect must be the magical effect for the armour, if that even exist in the game?

I have an rtx2060, this should work fine in theory.

I checked out this pre-generated paladin named "Sorscha", and I can see this effect, too. It looks even uglier on my end (see screenshot). I examined the armor with a customization mod and found out that this is because it is using the metal color "Light Prismatic", so the rainbow effect is deliberate. Not sure if it's supposed to look this bad though. It might be worse than it was in the past for some reason (btw, are you playing NWN Diamond or NWN EE? for me it's the latter).

This character is probably made for Hordes of the Underdark, which starts at a higher level, because it's meant to be played with the same character as Shadows of Undrentide. So if you didn't want to play through SoU, first you could use this high level pre-made character instead.

Anyway, I recommend you toggle off "Show pre-generated characters" below the character list and ignore them in the future. Just create your own character(s). The official campaign is meant to be played with a level 1 character without
magical equipment.

So then this is just this one character only then. Good news. :) The version is the enhanced edition.

I've created a fighter character at level 1. Poor and broke. :D

Not so much this one character as this specific color that her special armor was given. There's a small chance that you might encounter it again at some point - or not.

If you don't care for NWN's regular skill-based crafting system (SPOILER: It sucks! Waste of skillpoints and resources, IMO, just to create mostly common items that you can find lying around everywhere or buy cheap in shops), I highly recommend installing this mod as override (replacing the default crafting dialogue):

Customize Character Override Hak EE

It will allow you to customize the looks of your characters and their equipment for free, and should you ever come across a piece of equipment with the ugly rainbow effect again, you could just change the color to something more agreeable. For me this is a must have, one of the few mods I have installed at all times.

thank will give it a try if the issues appears.