ForMatter/Materials/gemstone/Ruby (Natural)

mat_gem_ruby_natural

Ruby (Natural)

corundum (Al₂O₃) chromium-colored, single-crystal natural · natural ruby, pigeon-blood ruby, Burmese ruby

highlast updated 2026-04-27

metallic 0.00

hue shift +0°

The same mineral as sapphire — corundum, aluminum oxide — colored deep red by traces of chromium, and traditionally distinguished from "pink sapphire" by saturation rather than hue (a debate that runs hot in gem-grading committees and cold elsewhere). Burmese ruby from the Mogok valley is the cultural reference; Mozambican ruby has carried the supply since the 2010s. Cr also makes ruby fluoresce — the same fluorescence Maiman exploited in the 1960 ruby laser.

α-Al₂O₃:Cr in trigonal crystal system, Mohs 9. Cr³⁺ replacing Al³⁺ at trace level (~0.1–1.0 wt%) provides red color + R-line fluorescence at 694 nm (the lasing line in the original ruby laser). Specific gravity 3.99. Refractive indices identical to sapphire. Heat treatment standard practice (disclosed); unheated Burmese stones command extreme price premium.

mechanical

mohs_hardness9
specific_gravity3.99

source: GIA; Hurlbut

optical

refractive_index_omega1.77
refractive_index_epsilon1.762
fluorescence_r_line_nm694

source: GIA; Maiman 1960

Sustainability

embodied carbon kg co2e per carat1.2
recyclabilityhigh — secondhand market stable
biodegradableFalse
certificationsGIA origin-determination report
localityprimary mining: Mozambique, Myanmar (Burma), Madagascar, Thailand

visual: saturated red — "pigeon-blood" Burmese ruby is the canonical color reference
tactile: cool, dense, hard

PBR starter values

Principled BSDF defaults derived from the sphere crystalline finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material.

# finish:      crystalline
albedo        #b81a30
metallic      0.00
roughness     0.05
ior           2.42
transmission  1.00
clearcoat     0.00
sheen         0.00
anisotropic   0.00

copy as JSON

{
  "albedo": "#b81a30",
  "metallic": 0.0,
  "roughness": 0.05,
  "ior": 2.42,
  "transmission": 1.0,
  "clearcoat": 0.0,
  "sheen": 0.0,
  "anisotropic": 0.0
}

Blender 4.x Python

# Blender 4.x — Principled BSDF
# Ruby (Natural) · finish: crystalline
import bpy
mat = bpy.data.materials.new(name="mat_gem_ruby_natural")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.4793, 0.0103, 0.0296, 1.0)
bsdf.inputs["Metallic"].default_value           = 0.000
bsdf.inputs["Roughness"].default_value          = 0.050
bsdf.inputs["IOR"].default_value                = 2.420
bsdf.inputs["Transmission Weight"].default_value = 1.000
bsdf.inputs["Coat Weight"].default_value        = 0.000
bsdf.inputs["Sheen Weight"].default_value       = 0.000
bsdf.inputs["Anisotropic"].default_value        = 0.000

KeyShot Python (lux)

# KeyShot 11+ — lux Python API, Generic material
# Ruby (Natural) · finish: crystalline
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_gem_ruby_natural", materialType="Generic")
mat.setProperty("diffuse",      (184, 26, 48))   # 8-bit sRGB
mat.setProperty("metallic",     0.000)
mat.setProperty("roughness",    0.050)
mat.setProperty("indexOfRefraction", 2.420)
mat.setProperty("transparency", 1.000)
mat.setProperty("coatingWeight", 0.000)

Substance pbrMetalRough

{
  "_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
  "_about": "Ruby (Natural) \u00b7 finish: crystalline",
  "baseColor": {
    "r": 0.4793,
    "g": 0.0103,
    "b": 0.0296
  },
  "metallic": 0.0,
  "roughness": 0.05,
  "ior": 2.42,
  "opacity": 0.0,
  "anisotropyLevel": 0.0,
  "_notes": "Channels listed are the standard Substance pbrMetalRough output. Drop into a Uniform Color node per channel, or as the constant input on a layered stack."
}

glTF 2.0 Metallic-Roughness

{
  "asset": {
    "version": "2.0",
    "generator": "ForMatter"
  },
  "materials": [
    {
      "name": "mat_gem_ruby_natural",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.4793,
          0.0103,
          0.0296,
          1.0
        ],
        "metallicFactor": 0.0,
        "roughnessFactor": 0.05
      },
      "extensions": {
        "KHR_materials_ior": {
          "ior": 2.42
        },
        "KHR_materials_transmission": {
          "transmissionFactor": 1.0
        }
      }
    }
  ]
}

USD Preview Surface

# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Ruby (Natural) · finish: crystalline
def Material "mat_gem_ruby_natural" {
    token outputs:surface.connect = </mat_gem_ruby_natural/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.4793, 0.0103, 0.0296)
        float   inputs:metallic     = 0.000
        float   inputs:roughness    = 0.050
        float   inputs:ior          = 2.420
        float   inputs:opacity      = 0.000
        float   inputs:clearcoat    = 0.000
        token   outputs:surface
    }
}

↓ download glTF material

Substitutes

Ruby (Synthetic, Verneuil Flame-Fusion)

Sapphire (Natural)

Citations

url · https://en.wikipedia.org/wiki/Ruby
url · https://en.wikipedia.org/wiki/Sapphire
book · Hurlbut & Klein, *Manual of Mineralogy*, 21st ed. (Wiley, 1999), corundum entry.

Concordance

House vocabulary — terms ForMatter uses with intent.

anisotropic: Direction-dependent. Wood reads differently along the grain than across it; rolled steel is stiffer along the rolling direction. The Principled-BSDF anisotropic input rotates the highlight to match.
application: What the thing IS, in the world. The third entity, peer of material and process. A water bottle, a chair, an extruded-aluminum profile.
BRDF: Bidirectional Reflectance Distribution Function. The math behind how a surface returns light for any incoming and outgoing direction. The PBR model is a parameterized BRDF.
channeled: A voice block written within a dead author's philosophy, marked and cited. Distinct from a verbatim quote. Roland Barthes channeled on PMMA reads like Barthes; the citation attributes the lineage.
choral fugue: ForMatter's register. Subject stated plainly (freshman tier), answered in technical and sensorial registers, countersubjects from linked processes and applications, citations as final stretto. Voice blocks where canon attaches.
clearcoat: A second specular layer over the base surface. Glossy plastics and lacquered woods get a clearcoat term in the PBR table. IOR 1.5 by default.
compatibility (process): Each process entry lists which materials it can work. The cross-ref renders as sphere pills so the gallery feeling extends inward.
confidence: Each entry tagged high / medium / low. A senior's low-confidence-with-three-citations beats a freshman's high-confidence-with-none. The label is a contract with the reader, not a brag.
crystalline (finish): A faceted-surface read — gemstones, glassy minerals, ice. Drives PBR defaults: IOR 2.42 (diamond), transmission 1.0, low roughness.
derive_pbr(): The build's single source of truth — sphere palette + finish enum → Principled-BSDF starter values. One function feeds the entry-page table, the per-host snippets, the glTF export, and the Three.js Live Preview.
freshman / senior register: Two registers in every entry — the plain freshman description and the technical / sensorial one. Same database, two readers, no extra subscription.
glTF: GL Transmission Format — the open 3D-asset standard every modern app reads. ForMatter emits a .gltf material doc per material. Open standard, designer-friendly handoff.
IOR: Index of Refraction. How much light bends entering the surface. Air 1.0, water 1.33, glass 1.5, diamond 2.42. Drives transmission and the specular term.
iridescent (finish): Hue-shifted accent over base. Anodized titanium and niobium, opal, paraíba. Drives PBR defaults: medium metalness, sheen, clearcoat.
lite-PBR: ForMatter's PBR approach — Principled-BSDF starter values per entry, no measured BRDFs, no commercial assets. Honest reasonable defaults from the finish enum, per-entry numeric overrides where you have a real reason.
Live Preview: The Three.js shader ball that replaces the static CSS sphere on entry pages. Same derive_pbr() values, real-time lit, draggable. Optional — toggle in Preferences.
material: What the thing is MADE OF. The first entity. Aluminum 6061, white oak, soda-lime glass.
metallic (finish): Specular highlight, deep shadow rim. Drives PBR defaults: metalness 1, low roughness, IOR 1.45. Polished steel, gold, copper.
PBR: Physically-Based Rendering. The shading model every modern 3D app uses, parameterized by metallic / roughness / IOR / transmission / clearcoat / sheen. ForMatter publishes starter values for every material entry.
Principled BSDF: Blender's name for the consolidated PBR shader. Most other apps ship the same shader under different names (Standard Surface, ShaderGraph, Substance). One node, every output.
process: How the material is MADE INTO the thing. The second entity. Cast, machined, kerf-bent, anodized, planished, granulated. Process is a peer of material, not a footnote.
quote: A voice block carrying a verbatim quotation from a living author, with citation. Distinct from a channeled block. Living = quote only; the rule is enforced at the schema layer.
roughness: Microsurface scatter. 0 is mirror-smooth; 1 is fully diffuse. Most real surfaces sit between 0.2 and 0.8.
sphere proxy: ForMatter's visible-character stand-in for every material. CSS-gradient driven by the entry's palette and finish, not a baked render. Honest about being a proxy, scales to six hundred entries cheaply, tweakable in one place.
substitute: A peer material that could fill a similar role. Cross-references render as sphere pills inside an entry — the gallery feeling extends inward.
transmission: How much light passes through. 1 is fully transparent; 0 is opaque. Glass, gemstones, clear plastics carry transmission.
voice block: A versal block where a real authored voice attaches to the material or process. Schema-tagged with status (living / dead) and mode (quote / channeled). Citations always.
woodgrain (finish): Directional sheen with grain ring. Drives PBR defaults: anisotropic 0.6, medium roughness, no metalness. Every wood entry.

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ForMatter

Materials and processes for people who design and make things.

A local-first library of materials, processes, and applications, equal weight, citable everywhere. Part of the renato.design ecosystem — sibling of Plenum, Specimen, Ingenue, gesture, graf, and the Renato Rhino plug-ins. Form and matter, inseparable.

Why this exists

Half of teaching materials is teaching how the material is made into the thing. The standard subscription library was always light on that half. The wedge here isn't better samples or a prettier interface — it's treating Process as a peer entity, not a footnote.

Rules of the house

Citations or it didn't happen. Every property number, every claim, every borrowed register has a traceable source.
Living authors are quoted only. Verbatim or not at all.
Dead authors may be channeled within their philosophy — marked, cited, never impersonated.
Confidence labeled honestly. A senior's low-confidence-with-three-citations beats a freshman's high-confidence-with-none.
Local-first. Works offline, no login, no subscription.

Sister apps

Ingenue — five voices argue about what to build from electronic parts. Where ForMatter teaches what the thing is made of, Ingenue proposes what the thing could be.
Plenum — vehicle codes through the camera, doo-wop register.
Specimen — iOS field-collection for design students.
renato.design — the rest.

Sources

Conway's Material World on raw materials, Lefteri's Making It on processes, Untracht and McCreight on metalsmithing, USDA Forest Products Lab on woods, GIA on gemstones, Schott / CoorsTek / Toray / Owens Corning datasheets, MakeItFrom for verifiable property numbers, ASM Handbook, ISO standards. Voice blocks: Barthes, Yanagi, Benjamin channeled within their philosophy; Lefteri verbatim. All cited.

v0.5 — 2026-04-27 · Phil Renato · renato.design · MIT-licensed code, CC BY-NC research content