950 Platinum in jewelry
Why choose platinum for your wedding and engagement rings?
At a glanceIn Swiss haute joaillerie and Place Vendôme ateliers, 950 Platinum is celebrated as the pinnacle of precious metals. Featuring 95.0% pure platinum content and an extraordinary density of 21.45 g/cm³, it enhances diamonds with unmatched brilliance and durability. This guide examines its metallurgy, working alloys, and wearer benefits.
Metallurgical Composition of 950 Platinum Alloys
Unlike 18-karat gold (which contains 25% base metals like copper and silver), jewelry platinum is 950 parts per thousand pure. The remaining 50 parts (5%) tailor the alloy's mechanical properties to specific manufacturing techniques:
| Alloy Designation | Alloying Element (50‰) | Mechanical Properties | Ideal Workshop Application | Annealed Hardness (HV) | Magnetic Behavior |
|---|---|---|---|---|---|
| Pt950 / Ruthenium (Pt/Ru) | 5.0% Ruthenium | Hard, excellent machining | CNC turned rings, watch cases | 130 – 140 HV | Completely non-magnetic |
| Pt950 / Cobalt (Pt/Co) | 5.0% Cobalt | Superior molten fluidity | Lost-wax investment casting | 135 – 150 HV | Weakly ferromagnetic! |
| Pt950 / Copper (Pt/Cu) | 5.0% Copper | Softer, ductile for forging | Hand-fabricated custom mounts | 110 – 120 HV | Completely non-magnetic |
| Pt950 / Iridium (Pt/Ir) | 5.0% Iridium | Traditional, highly ductile | Vintage jewelry, die-striking | 80 – 90 HV | Completely non-magnetic |
The Cobalt-Platinum Magnet Test Surprise
A critical testing nuance for jewelry appraisers:
Investment cast platinum alloyed with 5% cobalt (Pt950/Co) displays weak attraction to neodymium magnets!
This subtle magnetic response does not indicate a counterfeit or iron adulteration; rather, it confirms high-grade Swiss lost-wax precision casting.
4 Core Benefits of 950 Platinum for Fine Jewelry
1. Naturally White Forever: Platinum is naturally gray-white throughout its atomic structure. It requires no rhodium plating and will never yellow with age.
2. Superior Diamond Security: Platinum prongs have zero spring-back memory. Once formed over a diamond's girdle, they stay locked in place, providing unmatched protection for valuable gems.
3. Completely Hypoallergenic: 95% pure and nickel-free, platinum causes no contact dermatitis, making it ideal for sensitive skin.
4. Patina Without Metal Loss: When gold is scratched, microscopic slivers of metal are chipped away. When platinum is struck, the metal merely displaces plastically. It develops a rich satin patina while retaining 100% of its mass.
The Swiss Capricorn Guarantee Hallmark
Under the Swiss Precious Metals Control Act, platinum inspected by federal assay offices bears the numeric mark 'Pt 950' alongside the official guarantee stamp featuring the Head of a Capricorn (Steinbock).
Frequently Asked Questions (FAQ): 950 Platinum
Why does platinum feel so much heavier on the finger than gold?
950 platinum has a density of 21.45 g/cm³, compared to 15.50 g/cm³ for 18k gold. A platinum ring is approximately 35% to 40% heavier than an identical design in gold.
Can a platinum ring be resized?
Yes, but it requires a bench jeweler equipped with an oxy-hydrogen torch or precision laser welder due to the high temperatures involved (>1,700 °C).
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