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Let's use the index of refraction (IOR) well

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angelomaiota

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Apr 3, 2026

(Updated: 22 days ago)

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Let's use the index of refraction (IOR) well

Mastering Light Refraction with Flux: A Generic Guide to IOR-Based Material Control

A Physics‑Based Approach to Realistic Materials

Have you ever wondered why a diamond sparkles with rainbow fire, while a drop of water simply magnifies what’s behind it? The answer lies in a single, often overlooked number: the Index of Refraction (IOR).

IOR defines how much light bends when passing from air into a material – and how strongly that material reflects or transmits light. This guide explains how to use IOR values in your prompts with the V67 IOR LoRA for Flux, available at:
https://civitai.com/models/2513055/v67-ior

Stop guessing. Start bending light with precision.

What is IOR and Why Does It Matter?

The Index of Refraction is a dimensionless number that describes how light propagates through a medium. The higher the IOR, the more light slows down, bends, and reflects at the surface.

MaterialIOR RangeVisual EffectAir / Vacuum1.0No refraction, perfect transparencyIce1.31Slight bending, cold clarityWater1.33Moderate refraction, wet lookHuman skin (wet)1.42Natural sheen, moistureGlass1.5 – 1.6Strong refraction, causticsDiamond2.42Extreme dispersion, rainbow fire

By using (IOR:x.xx) tags in your prompts, you can achieve optically consistent materials – from dewy skin to crystal goblets, from liquid mercury to polished obsidian.

How to Use the V67 IOR LoRA (Generic Workflow)

Trigger Word

Always start your prompt with v67 (written once). Then describe your subject and include the IOR value in parentheses.

Basic syntax:

text

v67, [subject] (IOR:x.xx), [lighting], [camera angle], [quality tags]

ParameterValueLoRA weight0.65 – 0.85CFG Scale3.0 – 4.5Steps20 – 30 (Dev) / 4 – 6 (Schnell)SamplerEuler or DPM++ 2M Karras

Negative Prompt (optional but recommended)

text

nsfw, low quality, worst quality, blurry, children, glass people, text, watermark

20 Example Prompts – Full IOR Spectrum

These 20 prompts demonstrate the entire range from IOR 1.0 (air) to IOR 2.42 (diamond). No children, no glass people – just pure material science.

Air & Clouds (IOR 1.0)

  1. Cumulus clouds
    v67, cumulus clouds (IOR:1.0) at golden hour, soft volumetric lighting, perfect optical transparency, sky photography

Ice & Frozen Surfaces (IOR 1.31)

  1. Frozen lake
    v67, frozen lake surface at sunset (IOR:1.31), micro-surface scratches, bubbles trapped beneath the ice, cold blue tones, anisotropic reflections

  2. Melting ice cube
    v67, ice cube melting on slate (IOR:1.31), water puddle (IOR:1.33), refraction of background through the ice, macro

Water & Liquids (IOR 1.33 – 1.36)

  1. Water droplets on leaf
    v67, macro shot of water droplets on a green leaf (IOR:1.33), bright backlight, caustics, sharp edge reflections

  2. Human tear
    v67, a single tear rolling down a cheek (IOR:1.33), wet specular highlight on the tear edge, skin IOR 1.42, macro, emotional portrait

  3. Golden honey
    v67, honey dripping from a wooden dipper (IOR:1.36), viscous amber liquid, backlit warm glow, macro, food photography

  4. Mercury-like liquid metal
    v67, pool of liquid metal (IOR:2.0) on black rock, mirror reflection of alien sky, high surface tension, no wetting

Wet Human Skin (IOR 1.38 – 1.45)

  1. Wet face after swimming
    v67, close-up of a 22-year-old woman's face, wet skin (IOR:1.42), water droplets on forehead and cheeks (IOR:1.33), dripping from chin, soft window light

  2. Sweaty skin after workout
    v67, sweaty skin on shoulders (IOR:1.42), glistening under studio rim light, macro texture, realistic oil-water mix

  3. Wet lips
    v67, wet lips (IOR:1.38) with a single water droplet on lower lip, soft focus background, natural beauty lighting

Glass & Crystal (IOR 1.5 – 1.6)

  1. Red wine glass
    v67, crystal wine glass filled with red wine (IOR:1.55), strong backlight, rainbow caustics on white tablecloth, sharp rim reflections

  2. Empty whiskey tumbler
    v67, empty whiskey tumbler (IOR:1.52), ice cubes inside (IOR:1.31), condensation droplets on outer surface (IOR:1.33), dark bar background

  3. Magnifying glass
    v67, magnifying glass (IOR:1.52) held over a printed map, distorted letters visible, brass frame, macro, shallow depth of field

  4. Crystal vase with water
    v67, crystal vase (IOR:1.60) with fresh water (IOR:1.33), fluted glass texture, sunlight through window, caustics on wall

Plastics & Acrylics (IOR 1.45 – 1.55)

  1. Acrylic cosmetic jar
    v67, frosted acrylic jar (IOR:1.49) with pastel cream, backlit diffused glow, clean product render on white background

  2. Glossy plastic toy car
    v67, glossy red plastic toy car (IOR:1.50), sharp reflections of a window, smooth curved surfaces, studio lighting

Gemstones & Minerals (IOR 1.65 – 2.42)

  1. Diamond ring
    v67, diamond ring on black velvet (IOR:2.42), brilliant fire dispersion, rainbow sparkles, white spotlight, jewelry macro

  2. Polished obsidian dragon scale
    v67, polished obsidian scale (IOR:1.8), reflecting a distorted fiery environment, volcanic glass texture, conchoidal fracture edges

  3. Faceted black onyx
    v67, faceted black onyx (IOR:1.65) on leather surface, sharp specular highlights, dark background, luxury shot

Organic Translucency – Citrus & Honeycomb (IOR 1.35 – 1.49 + SSS)

  1. Lemon slice
    v67, slice of juicy lemon (IOR:1.35), light passing through moist pulp, subsurface scattering, backlit yellow translucency, macro food photography

Advanced Techniques: Double IOR and Layered Effects

Some materials require two IOR values – for example, human hair has a primary specular highlight (IOR ~1.55) from the cuticle and a secondary softer glow (IOR ~1.45) from internal reflection.

Hair example:

text

v67, single strand of blonde hair (primary IOR 1.55, secondary IOR 1.45), backlit, cuticle scales visible, silky longitudinal streak, macro

Fingernail (hard surface + subsurface scattering):

text

v67, human fingernail macro (surface IOR 1.53), wet-looking sharp highlight, soft SSS revealing pink nail bed, hard translucent keratin edge

Human iris (cornea + lens):

text

v67, extreme macro of multicolored iris (cornea IOR 1.376, lens IOR 1.39), bright catchlight, sharp radial fibers, natural eye texture

Pro Tips for Best Results

GoalPrompt StrategyStrong causticsAdd strong backlight, caustics on surfaceWet appearanceUse wet skin, water droplets (IOR:1.33), specular highlightsDiamond fireSpecify dispersion, rainbow sparkles, brilliant cutSubsurface scatteringAdd backlit, light passing through, translucencyGlass refractionInclude rim reflections, transparent shadows, background distortion

What to Avoid

  • Overloading every object with IOR tags (focus on 1–2 key materials)

  • Contradictions like matte diamond or rough glass

  • Extremely short prompts – Flux needs context for refraction

Why Use IOR Control?

Flux already handles textures and lighting beautifully. Adding explicit IOR values gives you predictable optical behavior – so a diamond always disperses light, and water always bends it. You don’t need a 3D renderer. You just need the right IOR number.

Ready to Bend Light?

Download the V67 IOR LoRA from Civitai:
https://civitai.com/models/2513055/v67-ior

Load it with Flux, write your prompts using v67 and (IOR:x.xx), and start creating materials that obey the physics of light.

Light doesn’t lie. Neither should your materials.

— A generic guide for the community

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