ForMatter/Materials/gemstone/Sapphire (Synthetic, Czochralski Pull-Crystal)
mat_gem_sapphire_synthetic_czochralski

Sapphire (Synthetic, Czochralski Pull-Crystal)

corundum (Al₂O₃), Czochralski-grown synthetic single crystal · Czochralski sapphire, CZ-grown sapphire, Kyropoulos sapphire (related method)
highlast updated 2026-04-27
metallic 0.00
hue shift +0°

The premium synthetic-sapphire route — pulled from a melt the same way silicon ingots are grown for semiconductors. Yields larger, optically purer single crystals than flame-fusion, with no curved growth striae. Used both for fine jewelry-grade synthetic gems and for technical applications like LED substrates, smartphone camera covers, and the largest sapphire watch crystals.

α-Al₂O₃ grown by Czochralski method (or related Kyropoulos / EFG techniques): seed crystal slowly pulled from molten alumina at 2050 °C while rotating, growing a single-crystal boule of arbitrary diameter and length. Free of curved striae and gas bubbles. Identifiable from natural sapphire only at instrumented level (lattice perfection signatures, characteristic absence of natural-mineral inclusions).

mechanical

  • mohs_hardness9
  • specific_gravity3.99
source: GIA; Crystal Systems / Rubicon technical references

optical

  • refractive_index_omega1.77
  • refractive_index_epsilon1.762
source: GIA

Sustainability

  • embodied carbon kg co2e per kg18
  • sourceEditorial estimate from ICE / Granta CES EduPack class databases — industry mean, with cradle-to-gate boundary unless otherwise noted. Embodied carbon for any specific product depends on supplier mix, recycled content, and energy grid; verify against a primary source before using these numbers in a sustainability claim.
  • recyclabilitymoderate
  • biodegradableFalse
visual
optically purer than Verneuil-grown stones, can be cut to dimensions Verneuil cannot reach

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        #2a4d8f
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": "#2a4d8f",
  "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
# Sapphire (Synthetic, Czochralski Pull-Crystal) · finish: crystalline
import bpy
mat = bpy.data.materials.new(name="mat_gem_sapphire_synthetic_czochralski")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.0232, 0.0742, 0.2747, 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
# Sapphire (Synthetic, Czochralski Pull-Crystal) · finish: crystalline
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_gem_sapphire_synthetic_czochralski", materialType="Generic")
mat.setProperty("diffuse",      (42, 77, 143))   # 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": "Sapphire (Synthetic, Czochralski Pull-Crystal) \u00b7 finish: crystalline",
  "baseColor": {
    "r": 0.0232,
    "g": 0.0742,
    "b": 0.2747
  },
  "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_sapphire_synthetic_czochralski",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.0232,
          0.0742,
          0.2747,
          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
# Sapphire (Synthetic, Czochralski Pull-Crystal) · finish: crystalline
def Material "mat_gem_sapphire_synthetic_czochralski" {
    token outputs:surface.connect = </mat_gem_sapphire_synthetic_czochralski/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.0232, 0.0742, 0.2747)
        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
Sapphire (Synthetic, Verneuil Flame-Fusion)
Sapphire (Natural)

Citations