Gold: fineness, stamps, scams, and 7 great confusions around it!
This is the complete guide to develop your understanding of gold. Everything you need to know BEFORE you can confidently buy gold is in this article.
Today, our goal is to take the mist out of the mysteries around buying gold once and for all.
Let's get started.
How is the Purity of Gold Measured?
There are two common ways to measure the fineness of gold, the millesimal fineness scale, and the karat measure.
Gold found in nature is commonly mixed with other metals such as silver, platinum, etc. You may often hear the word "alloyed", which means just that - "mixed with other metals".
Gold "fineness" is a common way to describe the purity of gold.
Briefly, fineness refers to the proportion of gold within an alloy and is expressed in parts per thousand.
|9 karat||14 karat||18 karat||22 karat||24 karat|
For example, a gold item that contains
85% gold and
15% silver is referred to as "
When gold contains close to
100% gold, it is referred to as "fine gold" or commercially "pure".
An industrial-scale chemical procedure is used to refine gold to a
.995 standard using the Miller chlorination process.
Once this standard is achieved, another purification process is used - the Wohlwill electrolytic process - to refine gold to
99.99% (also known as "four nine").
Purification can go to very high numbers, but
100% pure gold is essentially impossible to achieve.
The purest type of gold commercially available is
It often referred to as "five nine".
This "five nine" and above purity is widely used to produce collectible products that sell for a significant premium to their intrinsic commodity value.
The Royal Canadian Mint regularly produces commemorative coins from this "five nine" gold. One example of a 99.999% gold product is the coin below (face value - $200). Last time we checked, the market price of it was above $2000.
Just below the five nines are the four nines -
999.9 fine. American Buffalo and Canadian Gold Maple Leaf coins are made from this fine gold.
Most commonly, fine gold is
999, also known as "three nines fine".
This is the gold most commonly referred to as 24 karat gold, although technically, 24 karat gold is 100% pure. Gold manufacturers are legally allowed a half-karat tolerance in making gold products. We will speak about karats below.
So the first type of stamps you may find on the gold is the fineness expressed in a fraction of 1000.
Other words or letters can be stamped next to the fineness or karat marks, like
G.E.P and others.
They give additional information about the jewelry.
There is a lot of confusion around these marks.
From the buyer's perspective, it is handy to understand these marks and what they mean.
Let us break it down.
Gold Plating: 11 things every buyer has to know
Gold plating became popular because it gives a perfect look without the high price tag with gold. The plating quality depends on the thickness and purity of the gold coating, the base metal used, and the quality of craftsmanship. Once plated, it's almost impossible to tell real gold from gold plated jewelry just by looking at it.
Can you tell which one of these chains is gold and which one is gold-plated?
Answer: The first one is a Gold-plated metal chain priced at 128 CAD. The second one is a Gold metal chain priced at 6260 CAD.
Before plating, a piece of jewelry must be cleaned thoroughly. Dirt and oil on the base metal keep the gold layer from bonding correctly. Steam cleaning, ultrasonic cleaning, or electro-cleaning are the three best-known cleaning techniques.
If the base metal is allergic or tend to percolate into gold and change its color overtime the item may be coated in nickel first before plating with gold. Before proceeding to gold plating, the surface of the item has to be smooth, otherwise the plating will come out uneven. As the final layer, the jewelry is dipped in the containers with gold, and a positive electrical charge is used to fuse the gold onto the base metal. Once the gold plating thickness has been achieved, the jewelry is hung to dry. Depending on the thickness, type of gold, and lifestyle habits, the gold plated jewelry can last from 6 months to years!
This video shows you the gold plating process in action:
Any type of gold between 10K and 24K can be used in gold plating. The main difference will be in the final color. The higher the purity of the gold, the more gold-like the color will be.
Because a tiny amount of gold is used, the value of an article doesn't change much, regardless of the gold purity level. Gold plating mostly has little to no resale value and should not be considered an investment.
Gold plating, in general, can range in thickness between .17 to 2.5 microns.
Plating with a thickness of around .17 is called gold electroplated or gold wash/flashed. This is an extremely thin layer (about 0.05% of gold) and is only recommended for jewelry pieces sheltered from heavy wear and tear, like pendants and earrings. This thickness of plating wears off quite quickly.
The ideal thickness for gold plating is around .5 to 1.0 microns. While this might sound like a thin layer, it's sufficient even for jewelry pieces that are exposed to rough wear, like rings and bracelets.
Plating at around the 2.5-micron mark is quite thick and known as heavy gold plated. However, even this amount of gold plating is still very thin in terms of value, and the main benefit is that the plating lasts longer when it is thicker.
As with all things, there is a drawback to choosing gold plated jewelry. Tarnishing, fading, and replating are common issues you'll encounter.
Why gold-plated jewelry tarnish?
The problem is often not with the plating itself but with the base metal, prone to rusting and oxidizing. Over time, the molecules of the base metal eventually move into the gold layer, affecting its appearance. If the gold plating is very thin, it will discolor and start to look like tarnish quickly.
As mentioned above, this leeching of the base metal into the gold can be avoided if the jewelry is first plated with nickel to keeps the base metals from affecting the appearance of the gold. If this is done during the plating process, the gold is unlikely to tarnish.
When gold is plated or filled, the most commonly used stamps for jewelry are:
"GP", "G.P.", "gold electroplated", "gold plated", "G.E.", "G.E.P.", "electro‑plaqué d'or" or "or plaqué". These are acceptable quality marks that can be applied to an article plated with the gold of at least 10K. The thickness of the gold plate has to be at least 1 micrometer or larger.
"G.F." or "gold filled" or "doublé d'or". Gold-filled is like a gold plate, but the gold is heat-and-pressure bonded to the base metal. Gold must have a minimum purity of 10K gold, and the gold content must be at least 1/20th (5%) of the total weight of the entire item. For example, a mark of "1/20 10K G.F." refers to a gold-filled article that consists of 10 karat gold for 1/20th of its total weight. The layer of gold on gold-filled items is 5 to 10 times thicker than that produced by regular gold plating and 15 to 25 times thicker than that produced by gold electroplate.
"R.G.P." or "rolled gold plate" or "plaqué d'or laminé" Rolled gold plate and gold-filled may utilize the same manufacturing process, but the gold sheet used in rolled gold usually is less than 1/20th the total weight of the article. The sheet must still be at least 10 karat gold. Like gold-filled, the quality mark used for rolled gold plate articles may include a weight ratio and quality statement.
For example, the mark "1/20 10K rolled gold plate" says that the article had applied 10K gold and that the gold comprises 1/20 of the total weight of the article.
Note: each numeral in the fraction used must be in the same size of type and prominence as the entire quality mark. The mark can also be stamped in a short form. For example, "1/40 10K R.G.P."
"HGE" or "H.G.E." "HGE" can stand for both 'Heavy Gold Electroplate' or 'High Grade Electroplate,' meaning the piece is gold-plated with a slightly thicker layer than a GP or GE piece. Unfortunately, these pieces typically have little value since they have little gold content.
"HGP", "H.G.P. or H.G.E.P." Heavy gold plate signifies that the manufacturer used more than the standard amount of gold to plate the jewelry.
Neither HGE, "heavy gold electroplate," nor HGP, "heavy gold plate," have any legal meaning. They only indicate that the item is gold plated with higher than the standard amount.
"Gold Flashed", "Gold Washed" or "gold flash", "gold wash" According to Federal Trace Commission Consumer Information, you may also hear terms "Gold Flashed" or "Gold Washed". They describe products that have extremely thin electroplating of gold (less than .175 microns). This will wear off faster than gold plate, gold-filled, or gold electroplate. The FTC requires that if either the thickness of gold-electroplating is less than .175 microns, the product must be described as either "gold-flashed" or "gold-washed".
You can also hear Gold Clad / Karat Clad. In a technical sense – clad means that the gold layer was pressure bound to the underlying base metal. However, "gold clad" is a common synonym for any type of gold plating.
Here again – this means gold plated. As with all gold plated jewelry, some bonded gold jewelry has a thicker layer of gold plating than others – but the difference is negligible.
More detailed information can be found in different government regulation documents. For example, "Guide to the Precious Metals Marking Act and Regulations" gives a lot of details about Tolerance, Unauthorized markings, Frames, Flatware, Watch cases, etc.
Stay away from sellers that will try to sell you a piece of "gold" marked "EPNS." It stands for "Electroplated Nickel Silver," which is silverplate, meaning the piece is NOT gold.
Same thing with "gold" marked "EPBM." This stands for "Electroplated Britannia Metal." Typically, Electroplated Britannia Metal consists of 92% tin, 6% antimony, and 2% copper. NO gold at all.
What is Karat?
Karats are the little numbers stamped on a piece of gold in the format of "##" "##K" or "##KT" or "K##," where "#" means a number. The numbers refer to the type of gold and the actual gold content in the particular piece of jewelry.
There is a lot of confusion around two different words: "karat" and "carat."
A carat (also - metric carat) is a unit of weight used to measure the size of a gemstone such as a diamond.
A karat indicates the proportion of gold in an alloy out of 24 parts, so 18K gold is 18/24 parts gold.
Hundreds of years ago, when people needed some standard for weighing their gems, they turned to the carob tree.
Carob seeds were used to balance scales to measure weights. The carob's seed, in its turn, weighs approximately the same as the smallest gemstone. And since the seed was called a "carat," it became customary for stones that weighted approximately one seed to say: "It weighs one carat".
Early in the 20th century, the weight of the carat was set at 200 milligrams or 0.2 grams. So now, if you have a 4-carat diamond, it means it weighs 800 milligrams or 0.8 grams.
"Karats," in its turn, describe the purity of gold and have little to do with diamond weights. Gold karats are measured in portions of 24. For example, 24-karat gold is 100% gold or 1000 fine, but a 12-karat gold means that the alloy contains only 50% gold, i.e., it is 500 fine. Note that a gold alloy means that it will contain either another metal or a combination of metals.
For example, 22K Yellow Gold may contain:
Although "carat" and "karat" have distinct meanings in the jewelry world, the words are frequently confused. Here are a few examples showing "karat" being used to indicate the weight of a diamond instead of the purity of gold.
According to Merriam-Webster:
The bag—embellished with white gold and 18-karat diamonds — was sold at the first dedicated handbag sale at Christie's.
— The Mirror (UK), 12 June 2017
First came the robbery of his wife in Paris, a violent affair that included the theft of the 20-karat diamond engagement ring he gave her, worth a reported $4 million.
— The New York Times, 5 Jan. 2017
Interestingly, but using "carat" in place of "karat" to indicate the fineness of gold is considered acceptable.
Again according to Merriam-Webster:
Flare Audio's 24K gold-plated earplugs sell for more than $250. A pair of rhodium-plated plugs go for nearly $400. As the proverb goes, silence is golden. It must be. How else to explain the special edition ear protectors plated with 24-carat gold being sold for $258.66.
— David Hochman, Forbes, 30 Aug. 2017
Some countries, like Canada, made both names "karat" and "carat" official for gold marks.
"Guide to the Precious Metals Marking Act and Regulations" of Canada, section 6. "Articles other than plated articles" states:
"karat," "carat," "Karat," "Carat," "Kt.", "Ct.", "K," "C" or a decimal designation may be used to express the quality of gold of an article having a minimum quality of 9K or higher.
Karat vs "millesimal fineness"
|Number of Karats||Parts of Gold||% of Gold Purity||Millesimal Fineness|
|9K||9 / 24||37.5||375|
|10K||10 / 24||41.7||416 / 417|
|12K||12 / 24||50.0||500|
|14K||14 / 24||58.3||583 / 585|
|18K||18 / 24||75.0||750|
|22K||22 / 24||91.7||916 / 917|
|24K||24 / 24||99.9||999|
As you can see in the chart above, "millesimal fineness" refers to the percent of gold in an article, while karats refer to the ratio of gold to other metals in the piece.
Converting between the two is relatively easy. Here is how to use the number of karats to figure out your gold item's millesimal fineness or purity.
Say you purchase a ring that is 14K gold. Since the maximum amount of karats you can have is 24K, divide the 14 karats by 24. You will get .583, which means your ring contains 58.3% of pure gold.
Does a Karat Stamp Guarantee that a piece of jewelry is solid gold?
In short, no. Gold-plated jewelry can have karat stamps, but this stamp will indicate the purity of the gold plating, not of the entire piece.
For example, the stamp "14K GP" means that the item is gold plated and the plating is 14-karat gold, but the piece is made of another metal.
What is "P"?
A karat marking followed by ** "P"** indicates that the piece is plumb, meaning the purity is exact. For example, "10KP" means the item is precisely 41.7% gold. "P" as an indication of the exact content of gold was introduced because federal law allows the stamp to deviate .5 karats from the exact purity. A '10 K' stamp could be as low as 9.5 karats, but the plumb "10KP" stamp guarantees that the amount of gold is precisely 41.7%.
According to the Federal Trade Commission (FTC), "Guides for the jewelry, precious metals, and pewter industries" document products may be marked as "gold" without any karat qualifications if they are 24-karat gold (See § 23.3 Misrepresentation as to gold content).
If an item is less than 24K, it must have both the karat designation and the word "gold" to be equally visible.
A gold hallmark indicates that the gold content in jewelry has been evaluated and that the gold adheres to international standards of purity. The process of gold hallmarking is as unique to every country as it can be.
Let us look into hallmarking regulations in 3 countries: UK, USA, and Canada.
Why are precious metal articles hallmarked?
Gold is rarely used in its purest form. It is usually alloyed with lesser metals to achieve the desired strength, durability, color, etc.
It is impossible to detect the gold content of an item by just looking or touching the article. Therefore, it became a legal requirement to hallmark all articles consisting of gold if they are to be marketed as gold.
The UK Hallmarking Act 1973 states that it is considered an offense for any person:
To describe an un-hallmarked article as being wholly or partly made of gold, silver, or platinum. To supply or offer to supply un-hallmarked articles to which such a description is applied.
What needs to be hallmarked?
In the modern age, there are minimum weights at which hallmarking becomes a legal requirement. Every gold and palladium item weighing 1 gram or above, platinum weighing 0.5 grams or above, and silver weighing 7.78 grams or above must be hallmarked by law. Anything under these weights is exempt and won't feature a hallmark.
Since hallmarking was not always mandatory, all pre-1950 gold items that do not have any hallmarking may now be described and sold as gold as long as the seller can prove that it is of minimum fineness and was manufactured before 1950.
The Hallmarking Act 1973 stipulates using the hallmarking symbols to identify the precious metal.
Several other countries joined the Convention on the Control and Marking of Articles of Precious Metals, also known as the "Hallmarking Convention," the "Vienna Convention" or the "Precious Metals Convention", and follow the rules set by the UK.
So, as you see, the following three compulsory symbols must be present on the hallmark:
- Sponsor's mark
- Fineness mark
- Assay office mark
But what exactly are they?
The sponsor's mark.
The mark of the company that manufactured the piece. For example, Gemporia would use 'G' inside a shield.
The Fineness Mark.
This tells you how pure the metal is and is shown in parts per thousand. For the highest purity, the mark 999 is used rather than 1000 because it's virtually impossible to remove every last trace of impurity.
375 585 750 916 990 999 9 karat 14 karat 18 karat 22 karat 24 karat
The Assay office town mark.
London Birmingham Sheffield Edinburgh
The Date letter.
Until 1998 it was also a legal requirement to have a date letter stamped on the piece. It is optional now. Date letters run from A to Z, with a change in typeface and sometimes case every time the alphabet resets. Sometimes, the 'i' or the 'j' is skipped as they're too similar to be stamped as tiny letters, and they follow each other in the alphabet. It can create visual confusion.
Date letter designs were only standardized in more recent times. So if you will attempt to date an antique, you may need to research the specific date letter designs of the assay office that marked the piece.
2017 2018 2019 2020 2021
Gold-Traders website has compiled a gold hallmark identification wizard to help decode the markings stamped on your gold item. The project is ongoing, and Gold-Traders say that every effort has been made to ensure the accuracy of this wizard.
There is also the New Guidance Notes document, subtitled "Practical Guidance in relation to the Hallmarking Act of 1973" that has a wealth of practical information and charts.
In the U.S., hallmarking is not a legal requirement.
Did you expect that?
U.S. jewelry collectors and buyers look for maker's marks instead to assure that a piece is of high quality.
The problem is that the maker's marks are not regulated. There is no legal requirement even to register a maker's mark in the U.S.A. It is simply up to the maker to add their mark as they wish. So the maker's mark does not prove that a gold piece is as advertised.
Does it already sound to you like a business opportunity for creative minds?
But in reality, things are not THAT simple.
While no one seems to expect any changes in the U.S. legislation on hallmarking, U.S.A. buyers rely on their traditional system of self-regulation and public control over commodities and consumers' rights.
Americans are well known for suing any company if they suspect violations of consumer rights, which often leads to winning huge claims. You may say in the U.S.A. it is not the government hallmark, but the threat of legal prosecution, which serves the primary protection against underkarating problems.
In 1989, the Consumer Protection Division of the San Francisco District Attorney's (SFDA) office conducted three raids on the IPI Gold company. The owners were arrested and charged with selling underkarated and untrademarked gold jewelry. 15,000 pieces of jewelry were seized from IPI Gold as suspect underkarat merchandise, and the total civil exposure amounted to $80M in fines.
Because a proper assaying system does not exist, it is not uncommon in the U.S.A. that sellers bring on the market alloys where gold content is lower than declared. If price tags mention 10K gold, it may be, in reality, be 9K gold.
This "underkarating" happens mainly at shops selling cheap merchandise, at jewelry kiosks in shopping centers, during sales in general anywhere, where the cheap stuff is selling well.
Take, for example, the case of Attorney General Spitzer against two large distributors in New York City and 18 retailers from across the state. In 2001 they were fined for selling jewelry products that were falsely portrayed as "10 karat gold."
The investigation centered on two Manhattan-based distributors - Alishaev Brothers, Inc. and J&I Jewelry, Inc. - which imported and distributed "10 karat gold" products that actually contained insufficient quantities of gold. Alishaev and J&I Jewelry distributed these "underkarated" items mainly to the operators of small shops and retail vendors. Consumers were often low-income individuals and young people. In settling the cases, Alishaev and J&I Jewelry have agreed to halt shipments of "underkarated" products and pay $50,000 and $25,000 respectively in civil penalties and costs to the Attorney General's office. The 18 retailers separately entered into settlements that require them to stop selling underkarated jewelry and/or representing that the items are gold and pay fines collectively totaling nearly $50,000.
Overall, the best guarantee in the U.S.A. is the trademark of a manufacturer, who is entirely responsible before the law.
The Canadian system is close to the hallmarking system of the U.S.A. but has more regulations, requirements, and conditions.
At present, the Precious Metals Marking Act adopted in 1996 is in force. It served as the basis for developing the Canadian Hallmarking Regulations.
The Act and the Regulations are based on the buyer’s right to have correct information about the quality of a jewelry item.
Canadian system made physical persons engaged in jewelry sales or manufacturing responsible for valid hallmarking. This means: manufacturers, importers, wholesale traders, retail merchants, chief executive officers, managers, officers, or agents are personally responsible.
This kind of personal liability is an outstanding feature of the Canadian hallmarking system.
The hallmarking regulation requires that:
- any Canadian hallmark must be registered according to the Trademark Act;
- if an article is hallmarked in the United Kingdom, there is no need to affix additional hallmarks;
- there is no need for additional hallmarking for items brought from countries that genuinely and correctly indicates the quality of the precious metal by law;
- for Canadian jewelry, it is permitted to use the national mark to represent a maple leaf surrounded by the letter "C";
- it is allowed to apply any methods to affix a hallmark;
- it is permitted to use both commonly accepted abbreviations and inscriptions in English or French languages.
So, for instance, the gold coating of several micrometers in Canada can by law be marked as:
- "gold electroplate";
- "gold plated";
- "electro-plaque d'or";
- "or plaque".
Check also how the three hallmarking systems are different from the ones from other countries, check out the system accepted in India by The Bureau of Indian Standards (BIS) - another large supplier of gold on the international market.
What to Do If Gold Jewelry Is Not Stamped?
There can be many reasons why gold jewelry might not be stamped.
It could be an old piece that was never stamped. Or, its stamp could have worn off.
Of course, there is also the possibility that the item is forged and not gold at all.
Whatever the reason, make sure that you find out the karat of the piece before you buy it. The best way to do so is to have it tested for purity.
Most jewelers offer testing for gold to establish its karat. Gold testing kits are also available if you prefer to test the gold yourself.
This article goes over methods to verify if gold is real or fake in great detail.
In any case, it is not recommended to buy unmarked gold jewelry of which karat you are not sure.
Necessary Addendum: How is gold weight measured, and what is the problem with an Ounce of Gold?
If you start buying or collecting gold, there are also many more subjects that we need to touch as they can easily confuse anyone.
Let us begin with bringing the light onto the gold weight measurements.
When it comes to weighing gold, you will hear "ounces" all the time.
An ounce of gold refers to the weight of the gold measured in **troy ounces ("ozt"). **
Make sure you know the difference between the two popular abbreviations: oz and ozt. Ounce (oz), or avoirdupois ounce, is equivalent to 28.34 grams. Troy Ounce (ozt) is 31.10 grams. To be precise, one troy ounce is equivalent to 31.1034768 grams.
Each time "ounces" is mentioned in the context of gold, it means "troy" ounces, not avoirdupois ounce.
As you see, the troy ounce weighs about 10% more than an ounce, which makes a big difference when it comes to jewelry and precious metals.
"Troy ounces" as a unit of weight for gold have been used for centuries and are widely established worldwide.
Confusion does not stop here.
There is another distinction in the way oz and ozt are measured. 1 oz = 1/16 lb or 1 pound is precisely 16 oz. So most people think a troy pound must be heavier.
Sounds logical, right?
But it is right the opposite.
The abbreviation for troy pound is "lb t."
one troy pound is equal to
12 troy ounces, so
1 ozt =
1/12 lb t., which ends up being lighter.
1 lb t=
So in terms of weight, 1 pound of gold is approximately 80 grams more than one troy pound of gold.
To avoid confusion in international trades, everything related to precious metals and bullions is measured in troy ounces or kilos.
Without knowing this rule, you may get pretty confused.
Take a look at the two examples below:
First is 2021 Canada 1 oz Gold Maple Leaf coin.
As you see, it clearly says 1oz on the coin. But scroll down to Product Specifications, and you will see that Metal Content: 1 troy oz
Same with gold bullion bars.
The weight is measured in troy ounces. So technically, it should say 100 ozt.
Other systems to weigh gold.
Although the troy ounce and metric system are the most commonly established around the world, there are other systems to weigh gold used in different countries:
Pennyweight (abbreviated "dwt"): used as a unit of measurement of precious metals in North American and is equal to
1/20of a troy ounce, or
Tael (Hong Kong): Tael Hong Kong is equivalent to
1.2034 troy ounces.
Tael or Tahil (China): Tael China is equivalent to
1.6075 troy ounces.
Tael (Japanese): used in Japan and is equal to
1.20597 troy ounceor
Baht: used in Thailand and is equivalent to
0.4901 troy ounces.
Chi: used in Vietnam. Equivalent to
0.1206 troy ounces.
Cay or Luong: also common in Vietnam and equivalent to
1.206 troy ounces.
Don: used in South Korea. Like the Chi in Vietnam, it is equivalent to
0.1206 troy ounces.
Meshgal: used in Iran. Equivalent to
0.1482 troy ounces.
Tola (Vori, Bhori): used in India and other parts of the Middle East; it is equivalent to
0.375 troy ounces.
Māshā: Indian Units (Akbar System), which is still in use today. 1 māshā is equal to
Rattī: Indian Units (Akbar System). In use today. 1 rattī is equal to
Aana: used in India and Bangladesh, 1 aana is equal to
- Bhori: used in South Asian and Middle Eastern countries such as Dubai and Bangladesh. See Tola for measurements.
- Kampani tola: used in Nepal even after Nepal adopted the metric system by the Standard Weights and Measures Act, 1968, amended 1976. See Tola.
Mohar tola: Nepal Same as above. Equal to
Pau (Mohar): the use is the same as above. Equal to
Dharni: Nepal, same as above.
1 dharniequal to
Grain: used in dentistry to measure the weight of gold foil, a material to restore teeth. In the International System of Units, it is precisely
64.79891 milligrams. Official abbreviation: gr.
Note: in metric system except for g and kg or kgm you may encounter the use of "tons". Tons are primarily used in the mining industry. One metric ton of gold = 1,000 kg of gold and is equivalent to 32,150.7 troy ounces.
Other Units of Measurement
There are a couple of more abbreviations that you may encounter shopping for gold.
ppm, g/t and ppb
You may also encounter "ppm - "parts per million" and other abbreviations mentioned above when you try to assay your gold items to find out if an article is a real gold and how much gold is actually in it.
Gold is commonly reported by assaying laboratories either in ppm or ppb, depending on the metal and the analytical method used.
Take a look at this ad for Handheld XRF Gold Assayer:
Handheld XRF Gold Assayer is the ideal tool for fast and accurate analysis of all gold alloy samples, including gold jewelry, gold scrap, gold teeth, gold bars, gold pins, etc. The exact percentage of ppm of gold in any sample — as well as the complete alloy chemistry and gold karat determination — can be identified within a matter of seconds using the Handheld XRF Gold Assayer. With unparalleled accuracy, you can be sure that you have the right information regarding your gold composition every time.
One ppm of gold is equivalent to one gram per ton (g/t), i.e., one gram of gold per metric ton of rock. In mining, this means that it is necessary to mine, crush and leach one ton of rock to obtain one gram of gold.
Ppm and g/t are used interchangeably, as technically, they mean the same thing. In gold mining, g/t is more commonly used than ppm because most gold mines contain 0.4 to 4 grams of gold per metric ton of rock mined or greater.
In the exploration industry, gold is also commonly expressed as ** "parts per billion" (ppb)**. One ppb is equivalent to 0.001 ppm, or 0.001 g/t.
A ppb is a small unit of measurement and is particularly useful in the early stages of modern exploration. It is commonly used in soil sampling programs to detect minuscule gold anomalies, which could lead to a significant finding beneath the surface.
wt% - percentage by weight.
Last but not the least abbreviation that you may encounter is "wt%" Take a look at the following quote:
In 862 BC the Lydians were usingcoins made of a green gold-silver alloy known as‘electrum’ and composed of 73wt%Au and 27wt%Ag. - "Coloured Gold Alloys", Cristian Cretu, Elma van der Lingen. 1999, Gold Bulletin 32(4):115-126
"wt%" is used to show the relative proportions of elements in an alloy.
In the example above, 73wt%Au and 27wt%Ag means alloy of 73% Gold and 27% Silver. Most often you will encounter more compact way to express the same formula for an alloy where percentage may not be shown for the first element, but is shown for subsequent elements. For example: Au-27wt%Ag
Percentage by weight was introduced as different elements weigh different amounts. This type of percentage is often shown to avoid confusion.
Now it's your turn.
We hope you enjoyed our guide to the world of gold measurements.
Now we'd like to hear from you:
Which tip from today's guide you have found the most useful?
Which information was new for you?
Or maybe you found some inaccuracies?
Either way, let us know by leaving a quick comment below.