ForMatter/Materials/gemstone/Lab-Grown Diamond (HPHT)
mat_gem_diamond_lab_hpht

Lab-Grown Diamond (HPHT)

carbon allotrope, single-crystal lab-grown via belt or cubic press · HPHT diamond, high-pressure high-temperature diamond, Bel Air Diamond
highlast updated 2026-04-27
metallic 0.00
hue shift +0°

The other route to a real diamond grown in a lab — recreate the temperature and pressure of the mantle inside a steel-belt press, dissolve graphite in a metal solvent, and let single-crystal diamond precipitate onto a seed. Older method than CVD, still common, especially for industrial applications and for color-treatment of CVD or natural roughs. Same hardness, same brilliance, same chemistry as a mined diamond.

Single-crystal HPHT-grown diamond — graphite dissolved in a Fe-Ni-Co metal-solvent flux at 5–6 GPa and 1300–1600 °C, with single-crystal diamond seed. Cubo-octahedral crystal habit common in HPHT-grown stones (vs. cubic in CVD). Identifiable from natural diamond only at instrumented level — characteristic metallic-flux inclusions and fluorescence color-zoning patterns under DiamondView.

mechanical

  • mohs_hardness10
  • specific_gravity3.52
source: GIA Lab-Grown Diamond research summary

optical

  • refractive_index2.417
  • dispersion0.044
source: GIA

Sustainability

  • embodied carbon kg co2e per carat7
  • recyclabilitymoderate
  • biodegradableFalse
  • certificationsIGI Lab-Grown Report, GIA Lab-Grown Diamond Report
  • localityprimary production: Russia, Belarus, China, India, USA
visual
indistinguishable from natural diamond unaided

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        #f0f4ff
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": "#f0f4ff",
  "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
# Lab-Grown Diamond (HPHT) · finish: crystalline
import bpy
mat = bpy.data.materials.new(name="mat_gem_diamond_lab_hpht")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.8714, 0.9047, 1.0, 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
# Lab-Grown Diamond (HPHT) · finish: crystalline
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_gem_diamond_lab_hpht", materialType="Generic")
mat.setProperty("diffuse",      (240, 244, 255))   # 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": "Lab-Grown Diamond (HPHT) \u00b7 finish: crystalline",
  "baseColor": {
    "r": 0.8714,
    "g": 0.9047,
    "b": 1.0
  },
  "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_diamond_lab_hpht",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.8714,
          0.9047,
          1.0,
          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
# Lab-Grown Diamond (HPHT) · finish: crystalline
def Material "mat_gem_diamond_lab_hpht" {
    token outputs:surface.connect = </mat_gem_diamond_lab_hpht/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.8714, 0.9047, 1.0)
        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
Natural Diamond
Lab-Grown Diamond (CVD)

Citations