ForMatter/Materials/metal/18k Yellow Gold
mat_gold_yellow_18k

18k Yellow Gold

precious metal alloy, designer-jewelry yellow gold · 18 karat gold, 18kt, .750 gold, 750 yellow
highlast updated 2026-04-27
metallic 0.00
hue shift +0°

75% gold, 12.5% silver, 12.5% copper — the workshop default of European fine-jewelry tradition. Hard enough to make a wedding band you'll wear for forty years without it going oval, saturated enough in yellow that nobody mistakes it for plated brass, and the upper edge of what the European designer market routinely accepts. The line above which 22k territory begins, the line below which the 14k American market begins.

Au 75 / Ag 12.5 / Cu 12.5 nominal (the canonical "2N" / "3N" yellow per ISO 8654 color designations vary slightly with Ag:Cu balance). Solid-solution alloy across the full composition; copper-rich variants age-harden modestly via Cu₃Au ordering at ~250 °C. Vickers ~145 HV cold-worked. Liquidus ~895 °C. The color reads as standard "gold-yellow" in the Western fine-jewelry mental model.

mechanical

  • tensile_strength_mpa_annealed290
  • tensile_strength_mpa_cold_worked530
  • yield_strength_mpa_annealed130
  • hardness_vickers_annealed70
  • hardness_vickers_cold_worked145
  • hardness_vickers_age_hardened230
  • density_kg_m315580
source: World Gold Council casting alloy reference; ISO 8654

thermal

  • liquidus_c895
  • solidus_c850
source: World Gold Council technical bulletin

Sustainability

  • embodied carbon kg co2e per kg9800
  • 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.
  • embodied carbon recycled kg co2e per kg620
  • recyclabilityvery high — refiner-recoverable to fine gold and re-alloyed
  • biodegradableFalse
  • certificationsLBMA / RJC / Fairmined applicable to source bullion
visual
the reference yellow gold of European fine jewelry — slightly cooler than 22k, saturation calibrated against centuries of comparative tradition
tactile
harder under hand pressure than 22k, holds an edge; takes a polish that lasts
weight perception
heavy

PBR starter values

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

# finish:      metallic
albedo        #d4af37
metallic      1.00
roughness     0.25
ior           1.45
transmission  0.00
clearcoat     0.00
sheen         0.00
anisotropic   0.00
copy as JSON 
{
  "albedo": "#d4af37",
  "metallic": 1.0,
  "roughness": 0.25,
  "ior": 1.45,
  "transmission": 0.0,
  "clearcoat": 0.0,
  "sheen": 0.0,
  "anisotropic": 0.0
}
Blender 4.x Python 
# Blender 4.x — Principled BSDF
# 18k Yellow Gold · finish: metallic
import bpy
mat = bpy.data.materials.new(name="mat_gold_yellow_18k")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.6584, 0.4287, 0.0382, 1.0)
bsdf.inputs["Metallic"].default_value           = 1.000
bsdf.inputs["Roughness"].default_value          = 0.250
bsdf.inputs["IOR"].default_value                = 1.450
bsdf.inputs["Transmission Weight"].default_value = 0.000
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
# 18k Yellow Gold · finish: metallic
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_gold_yellow_18k", materialType="Generic")
mat.setProperty("diffuse",      (212, 175, 55))   # 8-bit sRGB
mat.setProperty("metallic",     1.000)
mat.setProperty("roughness",    0.250)
mat.setProperty("indexOfRefraction", 1.450)
mat.setProperty("transparency", 0.000)
mat.setProperty("coatingWeight", 0.000)
Substance pbrMetalRough 
{
  "_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
  "_about": "18k Yellow Gold \u00b7 finish: metallic",
  "baseColor": {
    "r": 0.6584,
    "g": 0.4287,
    "b": 0.0382
  },
  "metallic": 1.0,
  "roughness": 0.25,
  "ior": 1.45,
  "opacity": 1.0,
  "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_gold_yellow_18k",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.6584,
          0.4287,
          0.0382,
          1.0
        ],
        "metallicFactor": 1.0,
        "roughnessFactor": 0.25
      },
      "extensions": {
        "KHR_materials_ior": {
          "ior": 1.45
        }
      }
    }
  ]
}
USD Preview Surface 
# USD Preview Surface — UsdShade.MaterialLook prim attributes
# 18k Yellow Gold · finish: metallic
def Material "mat_gold_yellow_18k" {
    token outputs:surface.connect = </mat_gold_yellow_18k/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.6584, 0.4287, 0.0382)
        float   inputs:metallic     = 1.000
        float   inputs:roughness    = 0.250
        float   inputs:ior          = 1.450
        float   inputs:opacity      = 1.000
        float   inputs:clearcoat    = 0.000
        token   outputs:surface
    }
}
↓ download glTF material
ProcessBrazing · Laser Cutting · SLA 3D Printing (Stereolithography) · CNC Milling · Sandblasting (Abrasive Blasting)
Substitutes
22k Yellow Gold
14k Yellow Gold
18k Rose Gold
18k White Gold (Palladium-Whitened)

Citations