{"id":96731,"date":"2026-06-21T15:04:29","date_gmt":"2026-06-21T15:04:29","guid":{"rendered":"https:\/\/cjwilliam.com\/wholesale\/platinum-identification-guide\/"},"modified":"2026-07-01T02:40:10","modified_gmt":"2026-07-01T02:40:10","slug":"platinum-identification-guide","status":"publish","type":"page","link":"https:\/\/cjwilliam.com\/wholesale\/platinum-identification-guide\/","title":{"rendered":"Platinum Identification Guide: PT950, PT900 & Platinum Hallmarks Explained"},"content":{"rendered":"

Platinum is the densest and rarest of the three main precious metals used in jewelry and bullion.<\/strong> About 30 times rarer than gold, significantly heavier, naturally white, and hypoallergenic. This guide explains platinum purity standards, how to read hallmarks worldwide, how to tell platinum from white gold, how to test it, and how purity affects what platinum is worth.<\/p>\n\n

Most general jewelry buyers cannot price platinum properly because the dealer market is smaller and spreads are wider than gold or silver. CJ William prices platinum off live PGM spot at the moment of transaction, with the math shown. See the We Buy Platinum in Miami<\/a> page for the buying process.<\/p>\n\n

Platinum Purity Standards<\/h2>\n\n
Purity<\/th>Platinum Content<\/th>Common Stamps<\/th>Where Used<\/th><\/tr><\/thead>
PT999<\/td>99.9 percent<\/td>999PT, .999, PURE PLAT<\/td>Investment bullion bars and coins<\/td><\/tr>
PT950<\/td>95 percent<\/td>PT950, 950PT, 950PLAT, 950<\/td>Most modern fine jewelry, fine watches<\/td><\/tr>
PT900<\/td>90 percent<\/td>PT900, 900PT, 900PLAT, 900<\/td>Vintage American jewelry, Japanese platinum<\/td><\/tr>
PT850<\/td>85 percent<\/td>PT850, 850PT, 850<\/td>US legal minimum, some European jewelry<\/td><\/tr>
PT800<\/td>80 percent<\/td>800PT<\/td>Rare, mostly antique European<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

PT950 (95 Percent Pure)<\/h3>\n

The dominant standard for modern fine jewelry and the highest-end watches. Cartier, Tiffany, Van Cleef, Bulgari, Harry Winston, Patek Philippe, Vacheron Constantin, A. Lange and Sohne, and platinum Rolex all use PT950 or equivalent. The 5 percent alloy is typically iridium, ruthenium, or palladium for workability.<\/p>\n\n

PT900 (90 Percent Pure)<\/h3>\n

Common in vintage American platinum jewelry (particularly Art Deco era) and Japanese platinum, where PT900 is the traditional standard. Slightly more durable than PT950 due to higher alloy content.<\/p>\n\n

PT850 (85 Percent Pure)<\/h3>\n

The US legal minimum to be called platinum. Below PT850, the piece must be described as a platinum alloy. Less common in fine jewelry than PT950 or PT900.<\/p>\n\n

Investment Platinum (PT999)<\/h3>\n

Effectively pure platinum, used in bullion bars from PAMP Suisse, Valcambi, Credit Suisse, Johnson Matthey, Engelhard, Royal Canadian Mint, and in coins (American Platinum Eagle, Canadian Maple Leaf, Australian Koala, Isle of Man Noble).<\/p>\n\n

Country-by-Country Platinum Hallmarks<\/h2>\n\n

United States<\/h3>\n

American platinum jewelry typically stamps PLAT, PLATINUM, PT, PT950, PT900, or PT850, often with a maker mark. Older American platinum (pre-1980s Art Deco) frequently uses PLAT or PLATINUM without a purity number, which by convention typically indicates PT900 or higher.<\/p>\n\n

United Kingdom<\/h3>\n

UK platinum has been officially hallmarked since 1975. The hallmark stack includes sponsor mark, standard mark (an orb with a cross for platinum), assay office mark (London leopard, Birmingham anchor, Sheffield rose, Edinburgh castle, Dublin harp), purity number, and date letter.<\/p>\n\n

France<\/h3>\n

French platinum uses two standards: 950 first standard (dog’s head, chien mark) and 850 second standard (Mercury head). French maker marks are diamond-shaped lozenges.<\/p>\n\n

Japan<\/h3>\n

Japanese platinum is traditionally PT900 (the long-standing Japanese standard) and stamped PT900, PT950, or PLATINUM. Major makers (Mikimoto, Tasaki) stamp the maker plus purity.<\/p>\n\n

Germany and Italy<\/h3>\n

German and Italian platinum typically stamp the parts-per-thousand purity (950, 900) plus a maker mark. Italian platinum from Bulgari and other major makers includes the maker number in a diamond plus the purity.<\/p>\n\n

How to Tell Platinum From White Gold<\/h2>\n\n

This is the most common confusion in fine jewelry. Both are silvery-white precious metals used in similar pieces. But they are valued very differently and should never be confused at point of sale.<\/p>\n\n

Property<\/th>Platinum<\/th>White Gold (18K)<\/th><\/tr><\/thead>
Density<\/td>21.4 g\/cm3 (heaviest fine jewelry metal)<\/td>~15 g\/cm3 (significantly lighter)<\/td><\/tr>
Color<\/td>Naturally white, stays white forever<\/td>Pale yellow alloy, rhodium-plated white<\/td><\/tr>
Plating<\/td>None needed<\/td>Rhodium plating wears off, needs re-plating<\/td><\/tr>
Hallmarks<\/td>PLAT, PT, PT950, PT900, 950, 900<\/td>18K, 750, 14K, 585<\/td><\/tr>
Patina with wear<\/td>Soft patina, no metal loss<\/td>Plating wears off, exposes yellow underneath<\/td><\/tr>
Skin contact<\/td>Hypoallergenic for nearly all<\/td>Some white gold contains nickel, causes reactions<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

Fastest field test: pick up the piece. Platinum feels noticeably heavier than white gold of the same size. The hallmark is the definitive answer; XRF confirms in seconds.<\/p>\n\n

How to Test Platinum<\/h2>\n\n

XRF Testing<\/h3>\n

The gold standard for non-destructive platinum testing. XRF reads platinum content and any palladium, iridium, or other PGM content in seconds without damage. Used by professional buyers, refiners, and assay offices worldwide.<\/p>\n\n

Acid Testing<\/h3>\n

Platinum-specific acid (aqua regia or specialized platinum test acid) applied to a small inconspicuous area. Real platinum does not react. White gold, silver, and base metals do react. Reliable but leaves a small mark.<\/p>\n\n

Magnet and Weight Tests<\/h3>\n

Real platinum is not magnetic, ruling out ferrous fakes. The weight test (platinum significantly heavier than visually similar metals at the same volume) is a good first-pass check but not definitive.<\/p>\n\n

How Hallmark and Purity Affect Platinum Price<\/h2>\n\n

For investment platinum bullion<\/strong> (PT999 bars and coins from recognized refiners), price is platinum content times live PGM spot, less a small dealer margin. Typical payout: 92 to 95 percent of spot.<\/p>\n\n

For platinum jewelry (PT950 and PT900)<\/strong>, price is platinum content times spot, less refining and handling. Typical payout: 80 to 88 percent of melt after XRF verification.<\/p>\n\n

For platinum watches and signed designer platinum jewelry<\/strong>, the watch market or jewelry secondary value almost always exceeds the platinum melt by many multiples. A platinum Patek 5970P, platinum Rolex Daytona 116506, or signed Cartier platinum solitaire is worth far more intact than as melted metal. Selling these to a melt-only buyer destroys most of their value.<\/p>\n\n

Frequently Asked Questions<\/h2>\n\n

What is platinum?<\/h3>\n

Platinum is a dense, naturally white precious metal, about 30 times rarer than gold, denser than gold, hypoallergenic. The standard metal for the highest-end fine jewelry and fine watches.<\/p>\n\n

What is the difference between PT950, PT900, and PT850?<\/h3>\n

PT950 is 95 percent platinum (most modern fine jewelry). PT900 is 90 percent (vintage American, Japanese standard). PT850 is 85 percent (US legal minimum to be called platinum).<\/p>\n\n

What platinum hallmarks should I look for?<\/h3>\n

American: PLAT, PT, PT950, PT900, PT850. UK: orb-and-cross plus purity. French: dog’s head (950) or Mercury head (850). Japanese: PT900 or PT950. German\/Italian: parts-per-thousand plus maker.<\/p>\n\n

How do I tell platinum from white gold?<\/h3>\n

Weight: platinum significantly heavier. Hallmark: PLAT\/PT\/950 vs 18K\/14K\/750\/585. Color: platinum stays white forever; white gold loses rhodium plating. XRF is definitive.<\/p>\n\n

How do I test if platinum is real?<\/h3>\n

XRF (X-ray fluorescence) is most reliable. Acid testing confirms but leaves a mark. Magnet rules out ferrous fakes. Weight is a good first check.<\/p>\n\n

Why is platinum priced differently than gold?<\/h3>\n

Historically platinum traded above gold; the relationship inverted in the mid-2010s. Platinum is less liquid in the dealer market, so spreads are wider.<\/p>\n\n

What about platinum watches?<\/h3>\n

Solid platinum watches from Patek, Vacheron, A. Lange and Sohne, AP, and platinum Rolex are valued at the higher of the watch market or platinum melt; almost always the watch market is multiples of the melt.<\/p>\n\n

Can platinum be sold without a hallmark?<\/h3>\n

Yes. XRF testing confirms platinum content regardless of stamping. The density of platinum is difficult to fake, so unstamped pieces passing XRF are confidently identified.<\/p>\n\n

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Selling Platinum in Miami<\/h2>\n

CJ William buys platinum in every purity, every form. XRF testing in our Surfside showroom. Live PGM spot pricing.<\/p>\n

We Buy Platinum in Miami<\/a><\/div>
Call (347) 510-0668<\/a><\/div>
WhatsApp<\/a><\/div><\/div>\n\n

Part of the CJ William Knowledge Library. See also Gold Karat Guide<\/a>, Silver Hallmark Guide<\/a>, Diamond Certification Guide<\/a>, Watch Reference Number Guide<\/a>, Antique Silver Identification Guide<\/a>, Herm\u00e8s Birkin Authentication Guide<\/a>, Luxury Asset Liquidation in Miami<\/a>, and We Buy Platinum in Miami<\/a>. CJ William, 9573 Harding Avenue, Surfside, FL 33154.<\/em><\/p>\n\n