What Does Gold Purity Mean, And Why Is It Important?

Jewelry Metals

What Does Gold Purity Mean, And Why Is It Important?

If you’re new to buying gold or someone has given you gold jewelry, chances are good that you have questions. These can include wondering about gold purity and what that means. What is gold made of? Can you buy 100% pure gold? What makes it less than pure?

What does gold “fineness” mean? What’s the difference between carats and karats? Why is gold so expensive? What do all those letters stamped on gold jewelry stand for? How can you know if your jewelry is genuine gold? How should you care for and clean gold jewelry? How much gold is in Fort Knox?

What Is Gold?

Gold is special in several ways. It’s the only metal that’s naturally yellow. Gold is non-toxic to the extent that gourmet chefs occasionally add gold leaf to food. It’s classified as a noble metal, as air and moisture don’t affect it. It doesn’t tarnish or corrode. Only one acid, aqua regia, a mixture of hydrochloric and nitric acids, dissolves gold.

Meteorites were the source of gold on Earth. The gold that now exists is all that there ever will be.

People have treasured gold since prehistoric times. They often associated it with the sun. It was originally named aurum, Latin for shining dawn. That name lingers as “Au,” which is gold’s symbol. It’s used in dozens of ways, including in jewelry, electronics, medicine, and coins.

What Is Gold Purity?

Gold has been found all over the world, both in the Earth’s crust and in seawater. Depending on where it’s mined, gold averages about 85% pure when extracted. It's typically mixed with other metals, and tons of rock and dirt are processed to yield a few ounces of gold. According to one source, approximately “130,000 to 140,000 tons” of gold have been mined since gold was discovered millennia ago. If all the gold were combined into one piece, it would form a cube measuring “63 feet in each direction.”

How Is Gold Purity Increased?

After it’s mined, gold must be processed and refined. Several methods exist for doing so. Some are environmentally friendly. Some are not. One process, the Wohlwill Process, uses electrolysis to purify gold ore. It’s an extremely expensive method, but it yields gold that is 99.999% purity. 

A more common process is the Miller Process. It involves the use of chlorine gas. It’s cheaper and easier than the Wohlwill process. However, it only yields purity of 99.95%.

What Is The Difference Between Gold Purity And Fineness?

If you’re buying gold as an investment, you usually want the purest that you can afford. Although you may invest in gold jewelry, you probably will purchase gold bars or coins. Fineness is an alternate word for purity. You may also see the term millesimal fineness, which describes gold purity in terms of parts per thousand.

Fineness in gold bullion is frequently described as “three nines” or “four nines.” That refers to the number of nines after the decimal point. The more nines, the purer the gold. Years ago, the Perth Mint offered bullion with six nines, which remains the purest gold ever sold. 

Three and four nines are the most commonly available now. As a practical matter, the decimal point is often dropped, so that gold that is 99.995% fine is referred to as 995 fineness, or simply 995 gold.

Gold jewelry for investment may be from .585 to .999 fineness. 24-karat gold, called fine gold, is three nines. Other gold jewelry is rated much lower.

What Is The Difference Between Carats And Karats?

Carat is the original word used to describe the purity of gold. It was also used to describe the weight of gemstones. Later, jewelers began using karat for gold purity. It’s never used for anything else. Some countries do not use karat, preferring to use carat interchangeably for gold purity and gemstone weight. 

Karats are fractions that describe the amount of gold in a piece of jewelry. Twenty-four is the maximum amount possible. The actual amount of gold is the top number of the fraction. Accordingly, 24/24 equals .999 gold. Less than 24 karats means that the object has alloys, which are other metals. In the United States, objects can only be sold as gold if they contain at least 10 karats of gold.

For example, 10-karat gold is 10/24 gold, or 41.7% gold, or 417 fineness. 22-karat gold is 22/24 gold, which is 91.7% gold or 917 fineness. Karats, percentages, and fineness all equally express gold purity. 

Why Is Gold So Expensive?

Gold is just a shiny metal, but it’s been highly valued since humans walked the face of the Earth. Why? There are several reasons, with gold’s beauty being the primary one. Another is its rarity. And gold symbolizes perfection and the highest standards for many people.

Gold is essentially indestructible, and it doesn’t change over time. All the gold that ever existed still exists. It’s soft and easy to form into shapes. It can be stretched into long threads without breaking or hammered into thin sheets.

Gold is expensive to mine. With technological advances, the cost of mining can be reduced to around $200 per ounce of gold, but it’s usually more. There are numerous other costs involved, including processing and refining. Gold is rare, desirable, and expensive to get out of the ground and into the hands of consumers. Factors like these make gold costly.

The price of gold varies almost minute by minute. This article was written in early October 2023, and the price then was $1,886.83 per ounce.

Why Isn’t My Jewelry Made From Pure Gold?

Pure gold is soft. It is easily damaged, and often won’t hold its shape even at room temperature. That’s okay for 24-karat gold bars or coins kept in temperature-controlled storage. It’s a problem for most jewelry.

Gold is strengthened by adding other metals, or alloys, to it. 22-karat gold, which is suitable for most jewelry, contains 2/24 of one or more alloys. Although theoretically any metal can be used as an alloy, the most common metals are:

  • Cadmium
  • Copper
  • Iron
  • Manganese
  • Nickel
  • Silver
  • Tin
  • Titanium
  • Zinc

The manufacturer must stamp the karat rating or fineness on the jewelry. The alloy is typically not identified. However, most alloys change the color of the gold and can potentially be identified that way.

If you are allergic to a particular metal used as an alloy, you may experience a reaction. Pure gold doesn’t cause reactions.

What Are The Colors Created By Alloys?

As described, the various metals added to gold may change the color, depending on the kind and amount used. For example, gold may be alloyed with silver, copper, or zinc and still look yellow. In rounded numbers, 22k yellow gold is 91.7% gold, 5% silver, 2% copper, and 1.3% zinc. Changing the alloys yields 22K rose gold, which is 91.7% gold and 8.4% copper.

Some rose gold includes silver and copper. Silver creates white gold, but some white gold may include copper, platinum, or manganese. Silver, cadmium, and zinc are used to create green gold. Adding iron turns gold blue. Cobalt oxide added to alloys makes black gold.

There is a range of each color, again depending on the alloy and the amount used. For example, there are at least four shades of green, from pale to dark. 

Alloys are beneficial because they add strength, but they also reduce gold purity. There are numerous variations, such as 18k yellow gold, consisting of 75% gold, with 15% silver and 10% copper added. 

What Do The Numbers And Letters On My Gold Jewelry Mean?

As noted above, your gold jewelry will be stamped with the karat or the fineness, such as 22k or 917 if it’s 22-karat gold. You may see letters as well. If you see EPNS or EPBM on the piece, it’s not gold. It is electroplated nickel silver or electroplated Britannia metal, respectively. Both have their uses, but they are not gold.

GE and HGE both designate a metal like brass that has gold electroplate. The difference is the thickness of gold deposited on the surface of the metal. The gold must be 10k. For GE, the layer must be at least seven millionths of an inch thick, and for HGE, it must be at least 100 millionths of an inch thick. GF refers to gold filled. At a minimum, the gold must be 10k, and it must comprise 1/20th of the weight of the object.

You may see other designations. Always ask the seller what each means.

How Is Gold Tested For Authenticity?

If you have doubts about the authenticity of your gold, the first thing to look at is the letters or numbers stamped on the object. If you’ve purchased from a reputable seller, those will provide accurate information. Incidentally, numbers such as 800, 925, or 950 reflect the fineness of silver, not gold.  

Are There Tests That You Can Do At Home?

Touch a magnet to your gold object. Magnets won’t stick to gold. They do stick to fakes and alloys. Gold is dense, so your gold object will sink when placed in a container of water. Fakes will float. Genuine gold that contains an alloy will tilt. Nitric acid doesn’t affect gold, but it discolors fakes. You can order specialized testing kits designed for gold.

These tests may not be definitive because disreputable sellers can include materials that fool the tests. However, you know you don’t have genuine gold jewelry if the color looks “off,” if it becomes discolored, or rusts. 

How Do Professionals Test Gold?

Professionals invest in sophisticated equipment to accurately test gold. One test measures the specific heat properties of gold. Equipment such as a scanning electron microscope detects metals other than gold in the object. Aiming an X-ray photon beam at a gold object reveals everything that isn’t gold in the piece.

How Should You Care For And Clean Gold Jewelry? 

Gold jewelry accumulates body oils and other matter when worn. That can dull it. Wearing jewelry that’s less than 24k is harmed when exposed to the chemicals found in hot tubs and swimming pools. It’s also harmed by products such as hair spray, creams, and lotions. 

It’s best to remove your jewelry for most activities, including washing dishes. You should wrap most pieces in a soft cloth and store them separately. That’s especially important for 24k pieces, as the gold is easily scratched or damaged.

Cleaning methods must take into account the alloys in the gold. Many of those are subject to tarnish. You must also consider any gemstones in the jewelry. If you purchase a commercial jewelry cleaner, make sure it’s suitable for gold. 

The best cleaning solution is a few drops of blue Dawn dishwashing soap, which cuts grease and oils, in warm water. Some experts add a few drops of ammonia to the solution; others say to avoid it. Let the piece soak for up to 20 minutes. If necessary, use a very soft brush to scrub it, then rinse with warm water. Gently dry it with a soft cloth.

Consult a jeweler for advice on cleaning gold jewelry that has gemstones. A professional will also inspect the prongs and settings to ensure that nothing is loose or damaged.

How Much Gold Is In Fort Knox?

The United States stores about half of its gold reserves at the Fort Knox Depository in Kentucky. Currently, approximately 147.3 million ounces are stored. It’s in the form of gold bars that weigh 400 ounces or 27.5 pounds each. The book value is $44.22 per ounce. The actual value is much higher and varies daily.

But that’s not all the gold the US has. Altogether, the US has a total of just over 261.4 million ounces of gold stashed. 

The experts at Philophrosyne are happy to answer any questions you may have about gold or other precious metals. They will accurately provide comprehensive information that will help you make a good choice.

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