Precious Metal Pt950/Pt900/Pt850
GB 11887 · ISO 9202
Pt950, Pt900 and Pt850 are standardized platinum fineness grades under GB 11887, alloyed with iridium, ruthenium, cobalt, tungsten or copper to set hardness and castability.
Reference datasheet — Pt950/Pt900/Pt850 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Pt950Ru-Ann condition
Pt950/Pt900/Pt850 tempers and conditions
Pt950/Pt900/Pt850 is supplied in 11 conditions, soft to hard. Pt950Ru-Ann is the default FabDigit quotes; the values on this page are for it.
- Pt999-Ann
- Pt900Pd-Ann
- Pt850Pd-Ann
- Pt950Cu-Ann
- Pt950Ir-Ann
- Pt950Ru-Ann
- Pt900Ir-Ann
- Pt950Co-Cast
- Pt950W-Ann
- Pt850Ir-Ann
- Pt950Ru-H
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Pt999 (fine platinum, ≥99.9% Pt), annealed | Pick annealed unalloyed fine platinum for investment bars, granulation and highest-purity items; 45% elongation and 40 HB give maximum ductility but are far too soft for stone-set jewellery. | 55 | 145 | 45 | 40 HB | 16.3 % IACS |
Pt900/Pd | Lightest and softest Pt900 option — chosen to cut weight and cost in large hollow pieces, at the price of poor scratch resistance. | 100 | 220 | 38 | 78 HB | 9.5 % IACS |
Pt850/Pd | Economy Pt850 for chain, hollow and lightweight goods where cost and formability outweigh hardness. | 130 | 280 | 33 | 100 HB | 7 % IACS |
Pt950/Cu | Low-cost Pt950 used widely in Asian chain and light jewellery; easy to melt and form but softest and slightly warmer in colour. | 140 | 310 | 32 | 110 HV | — |
Pt950/Ir | Softest of the common Pt950 alloys — pick for hand-forming, bezels and easy stone setting where maximum ductility matters. | 150 | 320 | 38 | 110 HV | — |
Pt950Ru-AnnDefault Pt950/Ru | The workhorse Pt950 for hand fabrication, wire, tubing and general casting — good hardness/ductility balance and bright white colour. | 190 | 400 | 35 | 130 HV | 40 W/m·K |
Pt900/Ir | Classic hard-wearing fineness for prong settings, wedding bands and antique-style mountings; noticeably stiffer than Pt950. | 200 | 380 | 28 | 130 HV | 6.9 % IACS |
Pt950/Co | The standard investment-casting Pt950: best fluidity and fine detail reproduction, but slightly magnetic and prone to grey polishing smut. | 230 | 420 | 20 | 135 HV | — |
Pt950/W | Higher-strength Pt950 for thin wire, spring elements and wear surfaces; harder to melt and less forgiving in casting. | 260 | 480 | 25 | 140 HB | 4 % IACS |
Pt850/Ir | Hardest standard jewellery fineness (also used for medical wire and electrodes) — best wear and prong retention, hardest to work. | 260 | 480 | 22 | 160 HV | 5.4 % IACS |
Pt950/Ru | Choose for spring clasps, thin wire, pin stems and any part needing scratch resistance without heat treatment. | 600 | 700 | 3 | 19 HRC | 5.5 % IACS |
What is Pt950/Pt900/Pt850?
Pt950, Pt900 and Pt850 are standardized platinum fineness grades under GB 11887, alloyed with iridium, ruthenium, cobalt, tungsten or copper to set hardness and castability. They are specified for a density of 20.7 g/cm3, 400 MPa tensile strength at 35 % elongation, 175 GPa modulus and a white surface that stays bright without plating; usual forms are cast blanks, sheet, wire and finished settings. The 1780 °C melting point makes melting and casting equipment-intensive, and the metal is soft and gummy to machine, so swarf capture and refining are part of the process. Pd950 is the lighter, lower-cost white alternative. Pt950/Pt900/Pt850 has a density of 20.7 g/cm³ (0.748 lb/in³), heavier than 96% of precious metal grades. It melts at 1,780°C (3,236 °F). Pt950/Pt900/Pt850 has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 56% of precious metal grades. Elongation at break is 35% and the elastic modulus is 175 GPa (25.4 Msi).
What is Pt950/Pt900/Pt850 used for?
- Rings
- Bridal jewelry
- Watch cases
- Investment casting jewelry
Advantages
- Readily welded — 90/100, better than 99% of precious metal grades
- High service temperature — 1,000°C (1,832 °F), better than 95% of precious metal grades
- Good corrosion resistance — 99/100, better than 93% of precious metal grades
- Stiff — 175 GPa (25.4 Msi), better than 91% of precious metal grades
- Ductile — tolerates forming and impact — 35%, better than 83% of precious metal grades
Limitations
- High embodied carbon — 30,000 kg CO₂/kg, worse than 100% of precious metal grades
- Heavy — 20.7 g/cm³ (0.748 lb/in³), worse than 96% of precious metal grades
- Low electrical conductivity — 5.7 % IACS, worse than 93% of precious metal grades
- Poor heat conductor — 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 85% of precious metal grades
Pt950/Pt900/Pt850 properties
Typical room-temperature values for Pt950/Pt900/Pt850-Pt950Ru-Ann; bars are the position among precious metal grades.
Physical3
Pt950/Pt900/Pt850 has a density of 20.7 g/cm³ (0.748 lb/in³), heavier than 96% of precious metal grades. It melts at 1,780°C (3,236 °F).
Mechanical11
Pt950/Pt900/Pt850 has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 56% of precious metal grades. Elongation at break is 35% and the elastic modulus is 175 GPa (25.4 Msi).
Thermal6
Pt950/Pt900/Pt850 is rated for continuous service to 1,000°C (1,832 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 85% of precious metal grades. Thermal expansion is 9 µm/m·K (5 µin/in·°F).
Electrical3
Pt950/Pt900/Pt850 conducts electricity at 5.7 % IACS, worse than 93% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (99/100), better than 93% of precious metal grades.
Sustainability4
Producing a kilogram of Pt950/Pt900/Pt850 takes about 300,000 MJ of energy and emits 30,000 kg of CO₂ — more than 99% of precious metal grades. Typical recycled content is 28%.
Manufacturability8
Pt950/Pt900/Pt850's machinability is fair (35/100, worse than 73% of precious metal grades); weldability excellent (90/100); formability excellent (85/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the precious metal family
Yield strength against density for every precious metal grade FabDigit runs. Pt950/Pt900/Pt850 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Pt950/Pt900/Pt850
Is Pt950/Pt900/Pt850 easy to machine?
Soft and gummy — use sharp, high-rake carbide or HSS tools, light depths, high speed with flood lube, and capture all swarf for refining.
Can Pt950/Pt900/Pt850 be welded?
Excellent: pulsed laser or oxy-hydrogen/oxy-acetylene fusion welding without flux; Pt solders (Pt-Au-Pd) available for graded joining temperatures.
Can Pt950/Pt900/Pt850 be formed, bent or molded?
Very ductile when annealed (anneal 1000–1200 °C, air cool); casting needs induction/centrifugal melting above ~1800 °C with phosphate-bonded investment and zirconia crucibles.
Pt950/Pt900/Pt850 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Rudefault Pt950/Ru alloy addition | 4.5 – 5.5 | 5 |
| Ir5% in Pt950/Ir, 10% in Pt900/Ir, 15% in Pt850/Ir | 0 – 15 | |
| Cocasting alloy Pt950/Co; renders alloy weakly magnetic | 0 – 5 | |
| Cueconomy Pt950/Cu and Pt850 variants | 0 – 15 | |
| PdPt900/Pd, Pt850/Pd lightweight variants | 0 – 15 | |
| WPt950/W high-strength wire variant | 0 – 5 | |
| Gaoccasionally used with Cu/Co to lower melting range for casting | 0 – 2 | |
| PtPt950 ≥95.0%; Pt900 ≥90.0%; Pt850 ≥85.0% per GB 11887 / ISO 9202 fineness marks | ≥ 95 (balance) |
What surface finishes work on Pt950/Pt900/Pt850?
Polishes to a durable bright white without plating; use platinum-specific compounds and diamond pre-polish because the metal smears rather than cuts, and reclaim polishing dust.
Equivalent designations
Standards and trade names that resolve to Precious Metal Pt950/Pt900/Pt850 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ISO
- 9202
- GB (China)
- 11887
How much does Pt950/Pt900/Pt850 cost?
Pt950/Pt900/Pt850 is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Pt950/Pt900/Pt850 — frequently asked
What is Pt950/Pt900/Pt850 used for?
Pt950/Pt900/Pt850 is typically used for rings, bridal jewelry, watch cases and investment casting jewelry. In short: densest common jewelry metal; white without rhodium plating; flux-free fusion welding.
What is the yield strength of Pt950/Pt900/Pt850?
Pt950/Pt900/Pt850 has a typical yield strength of 190 MPa (27.6 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 56% of precious metal grades. Strength varies by condition: see the 11 listed tempers.
Is Pt950/Pt900/Pt850 easy to machine?
Not especially — machinability is rated fair (35/100, worse than 73% of precious metal grades). Soft and gummy — use sharp, high-rake carbide or HSS tools, light depths, high speed with flood lube, and capture all swarf for refining.
Can Pt950/Pt900/Pt850 be welded?
Yes — weldability is rated excellent (90/100). Excellent: pulsed laser or oxy-hydrogen/oxy-acetylene fusion welding without flux; Pt solders (Pt-Au-Pd) available for graded joining temperatures.
What surface finishes work on Pt950/Pt900/Pt850?
Polishes to a durable bright white without plating; use platinum-specific compounds and diamond pre-polish because the metal smears rather than cuts, and reclaim polishing dust.
Can Pt950/Pt900/Pt850 be formed, bent or molded?
Very ductile when annealed (anneal 1000–1200 °C, air cool); casting needs induction/centrifugal melting above ~1800 °C with phosphate-bonded investment and zirconia crucibles.
What is the maximum service temperature of Pt950/Pt900/Pt850?
Pt950/Pt900/Pt850 is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Pt950/Pt900/Pt850 cost?
Pt950/Pt900/Pt850 is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ISO 9202 Jewellery — Fineness of precious metal alloys — ISO (2019)
- ASM Handbook Vol.2 — Properties of Precious Metals and Alloys — ASM International (1990)
- Noble metal alloy data (Pt-Ru, Pt-Ir, Pt-Co jewellery alloys) — Johnson Matthey (2020)
- Platinum Metals Review — platinum jewellery alloy properties — Johnson Matthey (2002)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.