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Financial Technology

How Gold Purity Works: Karats, Fineness Stamps and What They Mean for Value

Karats, fineness numbers and hallmarks tell you how much gold is actually in a piece of jewelry. Here is a plain-language guide to reading those marks and understanding why purity matters when you sell.

Ecosystem Intelligence Desk

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Lumo: The Next Chapter

Lumo, an affiliated directory of local cash-for-gold buyers at lumo.gold, exists to help people find places to sell gold. Before comparing buyers, though, it helps to understand what you actually have. The single biggest factor in a gold item’s metal value, after its weight, is its purity. This guide explains how purity is measured, how to read the stamps on jewelry and coins, and why two rings that look alike can be worth very different amounts.

Why Gold Is Almost Never Pure

Pure gold is beautiful but soft. It scratches, bends and wears down easily, which makes it impractical for rings, chains and other jewelry worn every day. To make gold more durable and to change its color, jewelers mix it with other metals such as silver, copper, zinc, nickel or palladium. The resulting mixture is called an alloy.

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The proportion of gold in that alloy is its purity. The more gold, the richer the color and the higher the metal value per gram. The less gold, the harder and more durable the piece, and the lower its value as metal.

The Karat System

In the United States and many other countries, gold purity is expressed in karats, abbreviated K or kt. (This is different from the carat used to weigh gemstones, though the words share an origin.) The karat system divides gold into 24 parts. Pure gold is 24 karats. Each karat represents one twenty-fourth of the total.

Common karat values and their approximate gold content:

  • 24K: about 99.9 percent gold, often described as fine gold.
  • 22K: about 91.7 percent gold, common in jewelry in parts of South Asia and the Middle East and in some bullion coins.
  • 18K: 75 percent gold, popular for fine jewelry.
  • 14K: about 58.3 percent gold, the most common choice for jewelry in the United States.
  • 10K: about 41.7 percent gold, the lowest karat generally sold as “gold” jewelry in the U.S.
  • 9K: 37.5 percent gold, common in the United Kingdom and some other markets.

To calculate the gold fraction yourself, divide the karat number by 24. A 14K ring is 14 divided by 24, or roughly 58 percent gold.

Fineness Numbers

Many items, especially those made in Europe or for international markets, are stamped with a three-digit fineness number instead of, or in addition to, a karat mark. Fineness expresses purity in parts per thousand.

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  • 999 or 999.9: fine gold (24K).
  • 916 or 917: 22K.
  • 750: 18K.
  • 585: 14K. The figure is slightly higher than the exact 583 to ensure the alloy meets the 14K standard.
  • 417: 10K.
  • 375: 9K.

If you find a small “750” stamped inside a ring, that is a claim that the piece is 18 karat gold.

Hallmarks and Maker’s Marks

A purity stamp is only a claim. How much it can be trusted depends partly on where the piece was made.

In some countries, including the United Kingdom, precious metal articles above a certain weight must be tested by an independent assay office and stamped with official hallmarks before they can be sold as gold. These marks typically include a sponsor’s or maker’s mark, a fineness mark and the assay office’s symbol, sometimes with a date letter.

In the United States, there is no government assay requirement for jewelry. Federal law and Federal Trade Commission guidelines govern how gold may be marked and described. Under federal law, a manufacturer that stamps a quality mark is generally expected to stamp a registered trademark or maker’s mark alongside it, which helps establish accountability. Still, marks can be wrong, worn or deliberately misleading.

You may also see older marks such as “KP,” which stands for “karat plumb” and indicated that an item met its stated karat without falling below it.

What Gold Color Tells You, and What It Does Not

Gold comes in several colors depending on what it is alloyed with:

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  • Yellow gold is mixed mostly with silver and copper.
  • White gold is alloyed with white metals such as palladium or nickel and is often plated with rhodium for extra brightness.
  • Rose gold gets its pink tone from a higher proportion of copper.

Color does not indicate purity on its own. An 18K white gold ring and an 18K yellow gold ring contain the same proportion of gold. Very deep yellow can suggest higher karat, but lighting, wear and plating can make appearances misleading.

Purity and Value

The metal value of a gold item, often called melt value, depends on three things: its weight, its purity and the current market price of gold. In simple terms:

  1. Weigh the item, ideally in grams or troy ounces. One troy ounce is about 31.1 grams.
  2. Multiply the weight by the gold fraction (for example, 0.583 for 14K).
  3. Multiply the result by the current price of pure gold per unit of weight.

That calculation gives a rough idea of how much pure gold the item contains and what that gold is worth at the moment. What a buyer actually offers will be lower, because buyers must cover refining, testing and business costs. Lumo’s other guides explain spot prices and buyer spreads in more detail.

Purity matters a great deal. Two chains of the same weight, one 10K and one 18K, contain very different amounts of gold, so their metal values differ substantially.

Testing Purity

Reputable buyers usually verify purity rather than relying on stamps alone. Common methods include acid testing on a touchstone, electronic testers and X-ray fluorescence analyzers that measure metal composition without damaging the item. Asking how a buyer tests, and whether testing happens in front of you, is reasonable.

A Quick Summary

  • Karats measure gold in twenty-fourths; fineness measures it in thousandths.
  • Stamps are claims, not guarantees.
  • Color does not reveal purity.
  • Value depends on weight, purity and the market price.

This guide is general educational information. For a specific item, a qualified jeweler or appraiser can provide an expert assessment.

Quick check: What karat does the fineness stamp “750” indicate?

  1. 14K
  2. 18K
  3. 22K
Show answer

B. 750 means 750 parts per thousand, or 75 percent gold, which equals 18 karats.

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The institutional news desk of the Boston Made network. Reporting is researched from wire services including The Associated Press and local sources, and written by the desk.

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Corporate News

Boston-Based BOSSTOX Launches AI Infrastructure Intelligence Platform for Analysts and Investors

Boston-based BOSSTOX has released a new subscription platform tracking the evidence behind the AI infrastructure buildout — power, cooling, compute, and the companies making it possible.

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Hands on a keyboard near a green circuit board

Boston-based BOSSTOX has launched a new subscription intelligence platform focused on the physical and digital infrastructure underpinning the artificial intelligence buildout, the company announced this month.

The product, called BOSSTOX AI Infrastructure Intelligence, tracks evidence across power generation and grid interconnection, transformer supply chains, data center construction, cooling technology, servers and networking equipment, and cloud capacity commitments from major hyperscalers.

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Rather than forecasting where artificial intelligence models or applications are headed, the platform is built around what the company calls an “evidence layer” — a structured, citation-backed database of public filings, procurement records, construction permits, operator announcements and company disclosures. BOSSTOX says the system is configured with OpenAI-powered analysis but maintained with human review at every step, and that no relationship in the dataset is inferred without a cited source.

BOSSTOX is offering the product across three subscription tiers: a $299-per-month Monitor plan built around bottleneck monitoring and a weekly signal digest; a $799-per-month Signal plan aimed at deeper intelligence briefs and analyst-ready research; and a $1,500-per-month Enterprise plan that includes managed intelligence, private briefings and portal access.

The launch is aimed at analysts, researchers and investors looking for a structured view of where AI infrastructure capital is flowing and where supply constraints are forming, according to the company. BOSSTOX, part of the Boston Made, Inc. family of brands, also operates an educational membership site at info.bosstox.com offering source-grounded market-literacy content; the company notes that its educational content and tools are for informational purposes only and do not constitute investment, financial, legal or tax advice.

The AI Infrastructure Intelligence platform is available now at bosstox.com.

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Background

Much of the public conversation about artificial intelligence focuses on software: models, chatbots and applications. Behind that software sits a very physical industry. Training and running large AI models requires data centers full of specialized chips, servers and networking equipment, along with large amounts of electricity and cooling. Building that capacity involves utilities, grid operators, equipment manufacturers, construction firms and cloud providers, each with its own timelines and constraints.

Because these pieces depend on one another, a delay in one area can slow everything else. A data center cannot operate without a grid connection, a grid connection may depend on transformers and other equipment, and new equipment depends on manufacturing capacity. Analysts often describe these limiting factors as bottlenecks.

Much of the information about this buildout is public, but it is scattered. Companies disclose plans in financial filings and earnings calls. Local governments publish permits and zoning decisions. Utilities and grid operators release planning documents. Organizing that material into a coherent picture takes time, which is part of why structured research products exist.

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Evidence versus forecasts

Research on emerging industries generally takes one of two approaches. Forecasting attempts to predict where a market is headed, often using models and assumptions about future demand. Evidence-based tracking focuses on what has already been documented, such as signed contracts, issued permits and disclosed spending. The two can complement each other, but they answer different questions. Evidence shows what is happening now and what has been committed; forecasts estimate what might happen next and depend heavily on their assumptions.

What it means for readers following AI infrastructure

For anyone trying to understand the topic, whether out of professional interest or general curiosity, a few research habits apply to any source:

  • Go to primary documents. Company filings, regulatory records and official announcements are the foundation. Summaries are useful, but the original documents carry the details.
  • Separate evidence from interpretation. A permit or contract is a fact; a conclusion drawn from it is an interpretation. Good research makes the difference clear.
  • Check dates. Plans change. An announcement from a year ago may have been revised, delayed or cancelled since.
  • Be cautious with automated analysis. AI tools can help organize information, but their outputs should be checked against cited sources, which is why human review matters.
  • Remember the limits. Educational and informational content can build understanding, but it does not account for any individual’s circumstances.

Key terms

  • AI infrastructure: The physical and digital systems, including data centers, chips, power and networks, that support AI workloads.
  • Hyperscaler: A very large cloud computing provider operating data centers at massive scale.
  • Grid interconnection: The process of connecting a new power source or large electricity user to the electric grid, often involving studies and approvals.
  • Transformer: Electrical equipment that changes voltage levels so power can be transmitted and used safely.
  • Data center cooling: Systems that remove heat generated by computing equipment, using air, liquid or both.
  • Procurement record: A public record of a purchase or contract, often by a government agency.
  • Citation-backed: Supported by references to specific, identifiable sources.

What to watch

Readers who follow AI infrastructure generally keep an eye on several types of public information, without assuming any particular outcome:

  • Company disclosures about capital spending plans and data center projects.
  • Utility and grid operator planning documents describing new load requests.
  • Local permitting and zoning decisions for data center sites.
  • Reports on equipment lead times, such as those for transformers and cooling systems.
  • Announcements of new cloud capacity agreements and how they evolve over time.

Each of these sources can help readers form a more grounded view of how the buildout is progressing and where constraints appear.

This is educational content, not investment advice.

Quick check: In AI infrastructure research, what is a “bottleneck”?

  1. A type of AI chatbot
  2. A limiting factor, such as equipment or power, that slows the overall buildout
  3. A cooling fluid
Show answer

B. A bottleneck is a constraint in one part of the system that holds back progress elsewhere.

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E-Commerce

Beyond Gold: What Sellers Should Know About Silver, Platinum and Palladium

Gold gets the headlines, but silver, platinum and palladium turn up in jewelry boxes and drawers too. Here is how each metal is marked, tested and priced when you sell.

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Lumo Opens Online Marketplace for Precious Metals

Lumo, an affiliated directory of local cash-for-gold buyers with live prices at lumo.gold, centers on gold, but many of the people who go looking for a buyer discover they also own other precious metals. Silverware, platinum wedding bands and the occasional palladium piece all have metal value, and each works a little differently. This guide walks through the basics so sellers can sort what they have before they ask for an offer.

Why the Other Metals Matter

A typical drawer of “old jewelry” is rarely all gold. It may hold a sterling silver bracelet, a set of silver-plated flatware, a platinum engagement setting and a handful of costume pieces that contain no precious metal at all. Knowing which is which keeps a seller from two common mistakes: assuming everything shiny is valuable, and overlooking a heavy item that is worth more than it looks.

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Silver, platinum and palladium are all traded on world markets, and each has a published spot price that moves through the trading day. A local buyer’s offer is usually based on that spot price, the weight of pure metal in the item and the buyer’s own costs for testing, refining and running a business.

Silver: Common, Heavy and Often Plated

Silver is the precious metal most households own in quantity, usually as jewelry, flatware, serving pieces or coins. Its price per ounce is far lower than gold’s, so silver items need real weight before they add up to a meaningful sum.

  • Sterling silver is 92.5 percent pure silver and is usually stamped “925,” “Sterling” or “Ster.”
  • Coin silver, found in some older American pieces, is typically around 90 percent silver.
  • Fine silver is 99.9 percent pure and is stamped “999” or “Fine.” It is common in bullion bars and rounds.
  • Silver plate is a thin layer of silver over a base metal such as copper or nickel. Marks like “EP,” “EPNS,” “Silverplate” or “Quadruple Plate” signal plating, and plated items carry very little metal value.

Weighted pieces deserve special attention. Many sterling candlesticks, hollow-handled knives and some trophies are filled with cement, pitch or another material for stability. A buyer will account for that filler, so a candlestick that weighs a pound on a kitchen scale may contain only a fraction of that in actual silver.

Platinum: Dense, Durable and Easy to Miss

Platinum is a white metal that is heavier and more resistant to wear than gold. It became popular in fine jewelry, especially engagement and wedding rings, because it holds gemstones securely and does not tarnish. Because it looks similar to white gold and even to polished silver, owners sometimes do not realize what they have.

Platinum jewelry is usually much purer than gold jewelry. Common stamps include:

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  • “PLAT” or “PT” followed by a number, such as PT950 or PT900, indicating 95 or 90 percent platinum.
  • “Platinum” or “Plat” on its own, which in many markets indicates a high purity.
  • Mixed marks, such as “Iridplat” or “10% Irid,” which identify a platinum and iridium alloy common in older pieces.

Because platinum’s price has at times been above gold’s and at other times below it, sellers should check the current spot price rather than assuming platinum is automatically worth more.

Palladium: The Newer Jewelry Metal

Palladium belongs to the same family of metals as platinum. It is lighter than platinum, naturally white and hypoallergenic, and it has been used in some wedding bands and as an alloying metal in white gold. Most palladium in the world is used in industry, especially in vehicle catalytic converters, which is one reason its price can swing sharply.

Palladium jewelry may be stamped “PD” or “Pall,” often with a number such as 950. Some buyers handle palladium routinely and others do not, so it is worth asking in advance whether a shop purchases it and how it tests it.

How Buyers Test These Metals

A reputable buyer does not rely on stamps alone, because marks can be worn, misleading or counterfeit. Common testing methods include:

  1. Visual and magnet checks. Precious metals are not magnetic. A strong pull from a magnet suggests a steel or nickel core, although a lack of attraction does not prove an item is genuine.
  2. Acid testing. A small scratch on a testing stone is exposed to acids formulated for different metals and purities. It is quick and inexpensive but leaves a mark on the stone, not usually on the item.
  3. Electronic testers. Handheld devices measure electrical properties to estimate purity.
  4. X-ray fluorescence (XRF). An XRF analyzer reads the surface composition without damaging the piece. It is fast and detailed, though it reads the surface, so thick plating can still require further checks.

Sellers are entitled to watch testing take place and to ask which method is being used.

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Understanding the Offer

An offer for any precious metal follows the same basic logic. The buyer estimates the weight of pure metal, multiplies it by a price tied to the current spot quote and then applies a percentage that covers refining, overhead and profit. That percentage varies from shop to shop and from metal to metal. Silver, which is bulky and lower in value per ounce, often carries a wider gap between spot and offer than gold does.

A few practical habits help:

  • Look up the spot price for each metal on the day you plan to sell.
  • Separate items by metal and by stamp before visiting a buyer.
  • Ask for the weight of each group and the price per gram or ounce being offered.
  • Get more than one quote, especially for larger lots of sterling flatware or platinum jewelry.

When Melt Value Is Not the Whole Story

Some items are worth more as objects than as metal. Signed designer jewelry, antique silver from well-known makers, collectible coins and pieces with significant gemstones may command more from a jeweler, antiques dealer or coin specialist than from a buyer who pays for metal content. If an item has a maker’s mark, a pattern name or a known history, it can be worth researching before selling it for scrap.

The same caution applies to gemstones set in platinum or palladium. Most metal buyers pay little or nothing for stones, so sellers may want to have significant stones assessed separately or ask whether they can be removed and returned.

A Simple Checklist Before Selling

  • Sort pieces into gold, silver, platinum, palladium and unknown.
  • Use a loupe or magnifying glass to read stamps, and note them on a list.
  • Set aside anything signed, antique or set with notable stones.
  • Check current spot prices for each metal.
  • Confirm in advance that the buyer purchases the metals you have.
  • Keep your list and the buyer’s receipt together for your records.

Precious metals other than gold are easy to overlook, but a little sorting and a few good questions help sellers understand exactly what they own and what a fair conversation with a buyer looks like.

Quick check: A spoon is stamped “EPNS.” What does that most likely tell a seller?

  1. It is sterling silver at 92.5 percent purity
  2. It is silver plate over a base metal with little metal value
  3. It is a platinum and nickel alloy
Show answer

B. “EPNS” stands for electroplated nickel silver, a thin silver coating over base metal, so its precious-metal content is minimal.

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Financial Technology

Selling Inherited Jewelry: Sorting Heirlooms From Scrap and Documenting Every Piece

Inherited jewelry often mixes treasured heirlooms, valuable pieces and simple scrap. This guide explains how to inventory a collection, read basic markings, decide what deserves an appraisal and document everything before selling.

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Lumo: The Next Chapter

Lumo (lumo.gold) is an affiliated directory of local cash-for-gold buyers, and one of the most common situations that brings people to such buyers is an inheritance. A jewelry box from a parent or grandparent can hold anything from costume pieces to fine antique jewelry, and it is easy to sell something for its metal weight when it was worth far more as a whole piece, or to keep worthless items while overlooking valuable ones. This guide offers a careful, step-by-step approach. It is general education, not legal, tax or appraisal advice.

Before You Begin: Check the Estate Situation

If the jewelry is part of an estate that is still being settled, make sure you have the right to sell it. Executors, family members and, in some cases, legal or tax professionals may need to be involved. Inherited items can also raise questions about valuation for estate purposes. When in doubt, consult a qualified attorney or tax professional before selling anything.

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It is also worth talking with family members early. Pieces with sentimental value may matter deeply to someone, and a conversation before anything is sold can prevent lasting regret.

Step 1: Make a Complete Inventory

Lay everything out on a clean, well-lit surface, ideally on a soft cloth to prevent scratches or lost stones. Give each piece a number and record:

  • A short description, such as “yellow metal ring with clear center stone.”
  • Any visible markings or stamps.
  • Approximate size and condition.
  • Any known history: who owned it, when it was acquired, where it came from.
  • Any original boxes, receipts, appraisals or certificates found with it.

Step 2: Photograph Everything

Take clear photos of each piece from several angles, including close-ups of markings, clasps and stones. Photograph pieces next to a ruler for scale. These images are useful for insurance, family records, appraisals and comparing buyer offers. Keep them stored safely in more than one place.

Step 3: Look for Markings

Many pieces carry small stamps indicating metal content or maker. A jeweler’s loupe or magnifying glass helps. Common markings include:

  • Karat marks for gold, such as 10K, 14K, 18K or 22K, or numerical equivalents such as 417, 585, 750 and 916, which indicate parts per thousand of pure gold.
  • Silver marks, such as 925 or “Sterling.”
  • Platinum marks, such as PLAT or 950.
  • Plated or filled marks, such as GP (gold plated), GF (gold filled), HGE (heavy gold electroplate) or RGP (rolled gold plate), which indicate only a thin layer of gold over another metal.
  • Maker’s marks or signatures, which can add significant value if the piece was made by a known designer or firm.

Markings are helpful but not definitive. Some genuine pieces are unmarked, especially older or repaired items, and some markings can be misleading. Testing by a professional provides more certainty.

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Step 4: Sort Into Categories

With your inventory in hand, sort pieces into broad groups:

  1. Keep: Items with strong sentimental value, regardless of monetary worth.
  2. Potentially valuable as whole pieces: Signed or designer jewelry, antique or vintage pieces with fine craftsmanship, pieces with significant gemstones, and items with notable history. These may be worth more than their metal content.
  3. Likely scrap: Broken chains, single earrings, damaged rings, worn or bent pieces with no special design or maker, and dental gold. These are typically valued mainly for metal content.
  4. Costume or non-precious: Items without precious metal markings that test as base metal. Some vintage costume jewelry has collector value, so do not discard it automatically.
  5. Uncertain: Anything you cannot identify. Set these aside for professional evaluation.

Step 5: Get Professional Opinions on Valuable Pieces

For items that may be worth more than scrap value, consider an independent appraisal before selling. An appraiser who is not also bidding to buy the item can give a more objective assessment. Look for appraisers with recognized gemological or appraisal credentials, and ask:

  • What type of value the appraisal reflects, such as fair market value or insurance replacement value, since these can differ substantially.
  • How fees are calculated. Many reputable appraisers charge a flat or hourly fee rather than a percentage of the item’s value.
  • Whether the appraisal will be provided in writing with photos and descriptions.

For fine or signed pieces, estate jewelers and auction houses may offer better outcomes than scrap buyers, though they involve different timelines and fees.

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Step 6: Handle Gently

Avoid aggressive cleaning before evaluation. Harsh chemicals, ultrasonic cleaners and abrasive polishing can damage stones, remove patina valued by collectors or loosen settings. A gentle wipe with a soft cloth is generally enough. Do not attempt to remove stones or disassemble pieces.

Step 7: Selling Scrap Gold Thoughtfully

For pieces in the scrap category, a few principles help:

  • Separate items by karat before visiting buyers, so each group can be weighed and priced accurately.
  • Know the approximate weight of each group, ideally measured on an accurate scale.
  • Check the current market price of gold for context, understanding that buyers pay less than the spot price to cover refining and business costs.
  • Get quotes from more than one buyer, and ask each to explain how they calculated their offer.
  • Watch the testing and weighing, and request a written receipt.

Step 8: Keep a Record

Document what you sold, to whom, when, for how much and how the price was calculated. Keep receipts and photos together with the original inventory. These records can be important for estate accounting, family communication and tax purposes.

The Bottom Line

Inherited jewelry deserves patience. By inventorying, photographing, reading markings, sorting carefully and seeking independent opinions on valuable pieces, families can honor sentimental items, recognize real value and sell scrap with confidence. A careful process protects both the money and the memories.

Quick check: What does a “GF” stamp on a piece of jewelry usually indicate?

  1. Solid 24-karat gold
  2. Gold filled, a layer of gold bonded over another metal
  3. Genuine freshwater pearls
Show answer

B. GF means gold filled, so the piece contains only a layer of gold rather than solid gold throughout.

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