Platinum Hallmarks on Jewelry: What Do These Stamps and Markings Mean?

Platinum hallmarks are official stamps certifying the purity and authenticity of platinum items and indicating exactly how much platinum an item contains.

The most common marks are Pt950 (95% pure), Pt900 (90%), Pt850 (85%), and Pt999 (99.9%, used for investment bullion). These hallmarks are regulated by authorities such as the FTC in the US and various assay offices in the UK and other countries in the world.

Not all platinum items are hallmarked. Antique pieces, very small items, and bullion bars lack these marks as they’re either unnecessary or impossible to stamp. Platinum hallmarks are typically not visible and are stamped in discreet locations such as inside ring bands or on clasps.

Platinum can’t carry gold or silver hallmarks like “750” or “925.” When purchasing platinum, checking for proper hallmarks is the most reliable way to verify authenticity and value.

Platinum Hallmarks: What Do These Stamps Mean?

What are Platinum Hallmarks?

Platinum hallmarks are official marks stamped on platinum jewelry and objects to confirm platinum item’s purity and authenticity. These stamps serve as guarantees the item contains the stated amount of of this noble, white metal.

Platinum hallmarks are regulated by hallmarking authorities such as the Federal Trade Commission (FTC) in the United States and London Assay Office, Birmingham Assay Office, and organizations governed by the UK Hallmarking Act 1973 in Great Britain.

Below is a list of most common platinum hallmarks, markings and stamps.

• Pt950 or PLAT950.  95% pure platinum (most common for fine jewelry);
• Pt900 or PLAT900. 90% pure platinum;
• Pt850 or PLAT850. 85% pure platinum
• Dog Head platinum hallmark. 85% pure platinum.
• Pt600 or PLAT600. 60% pure platinum.
• Pt500 or PLAT500. 50% pure platinum.

Additional internationally recognized platinum marks include “Pt950/Ir” (platinum-iridium alloy) and “Pt950/Ru” (platinum-ruthenium alloy), These hallmarks specify platinum alloy composition used in jewelry manufacturing.

Platinum hallmarks are important because platinum is often alloyed with other metals, and hallmarks tell you exactly what the numbers on platinum mean. Platinum markings also play a key role in gemological certification processes conducted by institutions like the Gemological Institute of America (GIA), which assess jewelry authenticity and quality.

Below is a useful platinum hallmarks chart that shows you all the stamps you’re likely to encounter in your day-today life.

How is Platinum Jewelry Hallmarked?

Platinum jewelry is hallmarked with stamps inside the piece to confirm its authenticity and fineness. Platinum jewelry hallmarks are applied by hand stamping, hydraulic pressing, or laser etching. Besides the finesse stamps other common symbols are sponsors marks (maker), date stamps and assay office stamps. These are all part of a complete platinum marking system used to identify platinum jewelry.

Most platinum jewelry is made of platinum 950, 900, 850 which means the most common hallmarks are Pt950, Pt900 and Pt850. These fineness standards are internationally recognized under systems such as the ISO 9202 standard for precious metals and are enforced by national hallmarking laws in countries like the United Kingdom, Switzerland, and Japan.

Assay office symbols include well-known marks such as the leopard’s head (London Assay Office), anchor (Birmingham), or scales (used in Switzerland), each confirming that the piece has been independently tested for metal purity. Additionally, manufacturer trademarks and date letters can appear alongside these marks to indicate the year of hallmarking and origin.

Is All Platinum Jewelry Hallmarked?

No, not all platinum jewelry is hallmarked. For example, older and antique platinum jewelry pieces from certain countries aren’t hallmarked, and this doesn’t mean those jewelry items are fake. This is particularly true for platinum jewelry pieces produced in the UK before the widespread enforcement of hallmarking laws like the UK Hallmarking Act 1973.

In modern times it’s expected for platinum jewelry to be hallmarked, especially in the US, UK and other countries with strict and enforced hallmarking regulations. Platinum labeling in the United States is handled by the Federal Trade Commission (FTC). In the UK, official assay offices like the London Assay Office are responsible for testing and stamping precious metals.

Very small platinum items or those below a certain weight threshold are exempt from hallmarking requirements even in countries where platinum hallmarking regulations are strictly enforced. These exemptions are legally defined (e.g., sub-1 gram thresholds in some jurisdictions) to account for the practical difficulty of stamping tiny items.

Does All Platinum Bullion Have a Hallmark?

No, not all platinum bullion is hallmarked. Platinum hallmarks aren’t present on bullion bars, because they’re considered raw material and not subject to the same hallmarking requirements as platinum jewelry.

Instead of traditional hallmarks many platinum bullion products feature refinery stamps, serial numbers, weight markings, and purity inscriptions such as “999.5” or “999.9”. These stamps and symbols are issued by accredited refiners like Valcambi, PAMP Suisse, or Johnson Matthey and they serve as replacement for official platinum hallmarks.

How To Check Platinum for Hallmarks and Purity? Is Platinum Stamped in a Visible Place? 

To check platinum hallmarks for purity and authenticity look for symbols, markings, engravings and stamps on the platinum pieces’ surface.

Platinum is never stamped in an overly visible place. Instead, Platinum hallmarks are found in inconspicuous places so as not to take away from the aesthetics of the jewelry piece. Good example is the inside or underside of the item (on clasps, bands, or handles),

Here’s an example of a platinum hallmark on a ring, conveniently hidden from view unless you specifically look for it.

What is 999 Hallmark on Platinum?

999 hallmark on platinum is a stamp that indicates platinum is 99.9% pure (999 parts per thousand). 999 platinum is also known as 24 karat platinum and it’s the highest purity platinum form available and the one used for IRA-approved platinum bullion. .999 purity level meets the requirements set by organizations such as the Internal Revenue Service (IRS) for inclusion in precious metals IRAs. It also meets the international standards like those defined by the London Platinum and Palladium Market (LPPM).

People wishing to open a platinum IRA account would be able to add 999 platinum coins and bars to their account.

Note: 100% pure platinum doesn’t exist as it’s technically impossible to prevent other metal particles from contaminating pure platinum.

What is 950 Hallmark on Platinum?

950 platinum hallmark is a stamp that shows the piece of jewelry is 95% pure platinum (950 parts per thousand), with the remaining 5% consisting of other metals (iridium, ruthenium, or cobalt).

950 platinum is primarily used in jewelry, particularly for modern rings and other high-end pieces. It’s also used in some types of watches.

Beyond jewelry, Pt950 finds applications in laboratory equipment, electrical contacts, and the glass industry.

Does Platinum 900 Have its Own Hallmark?

Yes, platinum 900 has its own hallmark and it’s either Pt900 or Plat900. The “900” mark means the item contains 90% pure platinum, with the remaining 10% consisting of other alloys added for alloy strengthening.

The marking you find can vary depending on the country of origin.

• In the U.S. the hallmark will often be “900 Pt” or “Pt900”.
• In the U.K. the hallmark typically includes a fineness mark (the number “900”), an assay office mark, and a sponsor’s mark.

Does Platinum 850 Have its Own Hallmark?

Yes, platinum 850 has its own hallmark. The Pt850 mark shows the millesimal fineness, or parts per thousand of pure platinum in the alloy with the Pt850 symbol indicating a piece of jewelry as 85% pure platinum. The two most common hallmarks for platinum 850 are 850 Plat or 850 Pt.

Platinum 850 is commonly used in jewelry, particularly in Japan and Hong Kong, for chain making, settings, and cast jewelry. These markets favor Pt850 alloys due to their balance between durability and cost.

Does Platinum 600 Have its Own Hallmark?

Yes, platinum 600 has its own specific hallmark, although the mark varies by region and is more descriptive than the hallmarks for higher-purity platinum alloys.

In the USA a jewelry piece containing 60% platinum is stamped 600Pt. 400(Other Metal), where” (Other Metal)” is specified by the manufacturer, such as 600Pt./250Co./50Cu./50Zn./50Ni.

There’s no official hallmark for platinum 600 in the UK. The minimum legal fineness for a UK platinum hallmark is 850 parts per thousand.

Does Platinum 500 Have its Own Hallmark?

Yes, platinum 500 has its own hallmark, but it’s not widely accepted and recognized across the globe. International standards like ISO 9202 set minimum fineness thresholds for platinum alloys, and 500 parts per thousand falls below commonly accepted levels for platinum hallmarking in many jurisdictions.

For example, there’s no official hallmark for platinum 500 in the UK. According to the UK Hallmarking Act 1973, the minimum legal fineness for a UK platinum hallmark is 850 parts per thousand.

FTC guidelines in the US stipulate the item must be marked to show both the percentage of pure platinum and the percentage of other metals for all jewelry with a platinum content between 500 and 950 parts per thousand.

A piece with 50% platinum might be stamped 500Pt, 500(Other Metal), where “(Other Metal)” would be specified by the manufacturer, such as 500Pt./250Co./150Cu./50Zn./50Ni.

Does Platinum/Iridium Alloy Has its Own Hallmark?

Yes, platinum/iridium alloy has its own hallmark.

Platinum/Iridium hallmark is a stamp that includes the percentage of pure platinum (usually 90%), followed by an abbreviation for iridium.

Common metal ratios in platinum/iridium alloy include 90% platinum and 10% iridium, and 95% platinum and 5% iridium. These two Pt/Ir alloys are used in jewelry design.

70% platinum and 30% iridium alloy is also possible but rare compared to the other two.

Does Platinum Sterling Has its Own Hallmark?

No, there’s no official or standardized hallmark specifically for platinum sterling. Platinum sterling is a hybrid alloy that doesn’t meet the legal fineness requirements for items to be stamped as platinum.

Platinum Sterling doesn’t qualify for a platinum hallmark as it contains a low percentage of platinum (sometimes as little as 3.5% to 5%) blended with sterling silver.

However, legally required marks must still be applied to indicate the metal content accurately. You’ll find a combination of sterling silver hallmarks like “sterling” or “925” and an additional stamp specifying the percentage of platinum, such as “5%Pt,” to disclose the full composition for jewelry made from platinum-sterling alloy,

Can Platinum be Stamped With the “925” Hallmark?

No, platinum can’t be stamped with the “925” hallmark. The “925” mark indicates that a piece is made of sterling silver. A piece stamped “925” contains 92.5% silver and 7.5% other metals, almost always copper.

Remember that platinum and sterling silver are visually similar, and non-experts are often fooled by the two metals placed side by side.

Can Platinum be Stamped “750”?

No, platinum can’t be stamped with the “750” hallmark because this mark signifies 75% gold (18k).

The “750” mark indicates that a jewelry piece is made of 18k gold, meaning it’s made from 75% pure yellow gold and 25% other metals, mostly copper, zinc, silver and nickel.

Check out my gold hallmarks guide to learn more.

What are the Common Hallmarks on Platinum Watches?

Common hallmarks on platinum watches are fineness marks like “Pt950” or “950”. These stamps indicate a platinum watch that contains 95% pure platinum, and 5% some other metal, most often ruthenium, iridium, palladium, cobalt, copper or gallium.

Other hallmarks include maker’s marks (also called sponsor marks) and assay office marks. These are symbols that verify the metal’s origin and quality through independent testing.

See image below for a platinum watch with a full set of hallmarks.

What Does the Stamp “958” on Platinum Mean?

The “958” mark means that a piece is made of Britannia silver. A piece stamped “958” contains 95.8% silver and 4.2% other metals, typically copper. Britannia silver is a silver standard legally recognized under the UK Hallmarking Act 1973 and is identified by the Britannia figure symbol used by British assay offices such as the London Assay Office.

There’s 0% platinum in Britannia silver. The “958” stamp is exclusively reserved for this high-purity silver alloy and is never associated with platinum under any international standard, including ISO 9202 for precious metals.

Platinum Hallmarks: What Do These Stamps Mean? Conclusion

Platinum hallmarks are official stamps that certify the purity and authenticity of platinum items. These small marks indicate exactly how much platinum an item contains, a crucial info since platinum is often alloyed with other metals.

The most common hallmarks include 950 (95% pure platinum, standard for fine jewelry), 900 (90% pure), 850 (85% pure), and 999 (99.9% pure, used for investment-grade bullion).

Items may also be marked simply as “PLAT” or “PT” to indicate platinum content. A useful platinum hallmarks chart or platinum purity chart can help you read and identify platinum jewelry markings at a glance.

Not all platinum jewelry or bullion is hallmarked. While typical in countries with hallmarking regulations like the US and UK, antique pieces, very small items, or investment-grade bullion bars lack these marks.

Hallmarks are usually found in inconspicuous locations, inside ring bands, on clasps, or on the underside of jewelry.

References:

• Silver or Platinum?- https://www.reddit.com/r/Hallmarks/comments/1azi3ot/silver_or_platinum/
• Platinum Ring- https://www.reddit.com/r/Hallmarks/comments/16wm6pz/platinum_ring/
• Anyone know what this stamp means? Supposedly made of platinum in the late 1930’s. No other stamps anywhere on the ring- https://www.reddit.com/r/jewelry/comments/s9s6pe/anyone_know_what_this_stamp_means_supposedly_made/
• Is this a common looking hallmark for a platinum ring? I’m only familiar with gold and silver marks- https://www.reddit.com/r/Platinum/comments/14sys6y/is_this_a_common_looking_hallmark_for_a_platinum/
• Platinum 600 Wedding Rings- https://kavalri.com.au/collections/platinum-600
• Platinum ring (850/1000) set with two old european cut diamo – Lot 88- https://www.maisonrc.com/en/lot/143853/23431551
• V -shaped No. 9.5 Ring PT900 Platinum x Diamond D0.36 Stamp about 4.3g V Character Ladies SA Rank- https://shop-nishikino7.com/en/products/v-shaped-9-5-ring-ring-pt900-platinum-x-diamond-d0-36-engraved-v-character-sa-rank
• Platinum Perfection Ring
  High Finish Flat Wedding Band Ring in 950 Platinum- https://www.tjc.co.uk/limited-stock-one-time-deal—950-platinum-fine-polished-band-ring-3191433.html
• Iridium Platinum Explained- https://www.georgianjewelry.com/blogs/news/iridium-platinum-explained
• 1930’s (?) platinum ring- https://www.reddit.com/r/Hallmarks/comments/1celnkg/1930s_platinum_ring/

• Platinum Wedding Band- https://www.newyorkestatejewelry.com/Platinum-Wedding-Band/Wedding-Bands/20222/4/item
• Platinum- https://www.langantiques.com/university/platinum-2/
• The Time+ Tide guide to universal hallmarks- https://timeandtidewatches.com/the-timetide-guide-to-universal-hallmarks/
• Platinum hallmarks chart- https://leonmege.com/leon-mege-hallmarks/
• Hallmarking Act 1973- https://www.legislation.gov.uk/ukpga/1973/43