How can i make the "ideal" electrum composition?

Jewelry Discussion
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I’ve been thinking about gold and metal alloy compositions, specifically electrum. If you know it its a naturally accurring alloy (in varying compositions) of gold, silver, and trace elements used in coinage from a few millenia BC to 500ish BC. Today it’s called “green gold” (not sure why because it really doesn’t look green to me) since electrum is more of a historical term. I’ve been reading a lot!

I’ve been trying to figure out what really makes “electrum” or green gold different from a traditional yellow gold 10/14/18k etc composition. Is it because its just gold and silver and doesn’t have other metals added in? But then some compositions I’ve looked up do?

I’m interested in tinkering with this because I think it’s a beautiful term for a metal alloy that would set the jewelry piece apart as unique in both brand/item marketing and perhaps its perceived value. I’m also interested in the slight color variations different compositions would make.

Here are the questions-
Let’s assume I’m using 50% gold in any composition. I can call this 12k regardless of the other metals, right? ie: “12k gold/ 12k gold electrum” ?

I was planning on starting with 50% gold and 50% fine silver and adjusting from there. Should I add a small amount of paladium or another metal for hardness? (usage will be rings, sculptural necklace pendants, lockets) Would it still be called electrum if it was since naturally accuring electrum also has other trace elements?

And if I’m casting this piece myself, and I’d like a tiny bit of some other metal for durability and hardness, would it be easier or acceptable to shortcut by making casting grain out of 50% gold and 50% sterling silver? Since sterling already has copper/other alloys?

I hope this all makes sense!

TLDR learning about gold compositions and trying to find the best one (metal quality, color, price) to produce “electrum” jewelry

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Interesting! Good questions.

I recently bought a few of these beauties: https://www.apmex.com//product/225602

I am thinking of ways to make a chain with them.

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Now thats green!!

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Science, Tech, Math › Science

Electrum Metal Alloy

Detail of inlay on a Mycenaean bronze dagger showing a lion hunt, 16th century

Print Collector/Contributor/Getty Images


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Science

By

Anne Marie Helmenstine, Ph.D.

Anne Marie Helmenstine, Ph.D.

Chemistry Expert

  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College

Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.

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Updated on February 28, 2019

Electrum is a naturally occurring alloy of gold and silver with a small amount of other metals. The man-made alloy of gold and silver is chemically similar to electrum but usually is called green gold.

Electrum Chemical Composition

Electrum consists of gold and silver, often with small amounts of copper, platinum, or other metals. Copper, iron, bismuth, and palladium commonly occur in natural electrum. The name may be applied to any gold-silver alloy that is 20-80% gold and 20-80% silver, but unless it is the natural alloy, the synthesized metal is more correctly termed ‘green gold’, ‘gold’, or ‘silver’ (depending which metal is present in the higher amount). The ratio of gold to silver in natural electrum varies according to its source. Natural electrum found today in Western Anatolia contains 70% to 90% gold. Most examples of ancient electrum are coins, which contain increasingly lower amounts of gold, so it’s believed the raw material was alloyed further to conserve profit.

The word electrum has also been applied to the alloy called German silver, although this is an alloy that is silver in color, not elemental composition. German silver typically consists of 60% copper, 20% nickel and 20% zinc.

Electrum Appearance

Natural electrum ranges in color from pale gold to bright gold, depending on the amount of the element gold present in the alloy. Brassy-colored electrum contains a higher amount of copper. Although the ancient Greeks called the metal white gold, the modern meaning of the phrase “white gold” refers to a different alloy that contains gold but appears silvery or white. Modern green gold, consisting of gold and silver, actually does appear yellowish -green. Intentional addition of cadmium may enhance the green color, although cadmium is toxic, so this limits the uses of the alloy. The addition of 2% cadmium produces a light green color, while 4% cadmium yields a deep green color. Alloying with copper deepens the color of the metal.

Electrum Properties

The exact properties of electrum depend on the metals in the alloy and their percentage. Generally, electrum has a high reflectivity, is an excellent conductor of heat and electricity, is ductile and malleable, and is fairly corrosion resistant.

Electrum Uses

Electrum has been used as currency, to make jewelry and ornaments, for drinking vessels, and as an exterior coating for pyramids and obelisks. The earliest known coins in the Western world were minted of electrum and it remained popular for coinage until about 350 BC. Electrum is harder and more durable than pure gold, plus the techniques for gold refining were not widely known in ancient times. Thus, electrum was a popular and valued precious metal.

Electrum History

As a natural metal, electrum was obtained and used by early man. Electrum was used to make the earliest metal coins, dating back at least to the 3rd millennium BC in Egypt. The Egyptians also used the metal to coat important structures. Ancient drinking vessels were made of electrum. The modern Nobel Prize medal consists of green gold (synthesized electrum) plated with gold.

Where Can You Find Electrum?

Unless you visit a museum or win the Nobel Prize, you best chance of finding electrum is to seek the natural alloy. In ancient times, the chief source of electrum was Lydia, around the Pactolus River, a tributary of the Hermus, now called the Gediz Nehriin in Turkey. In the modern world, the primary source of electrum is Anatolia. Smaller amounts also may be found in Nevada, in the USA.

Cite this Article

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I am not sure how you are using the quantity 50%. If 50% of the electrum alloy is 12K gold alloy and 50% is fine silver, then only 25% is 24K gold, 25% is the rest of what makes the 12K gold alloy and 50% is fine silver, I think. Is this what you intend?..Rob

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Oh no sorry, I meant that wouldn’t using 50% fine, pure gold produce a 12k electrum alloy?

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there’s no ‘ideal" electrum as the article on ancient electrum cites a large variation in gold and silver alloys, electrum was naturally found as an alloy as the article states… there are dozens more but this one was short and to the point…if you mean ideal as 50/50 gold and silver, then the easiest way to do that is to mix equal proportions of fine silver and fine gold together… the result will be a light green gold.
Mixing proprotions won’t be easy… becaue gold and silver have different atomic weights, you can to do it by volume percent rather than weight percent…If you do it by weigh percent by measuring an amount of a scale, you will have less than 50% gold as gold is much heavier than silver… one method is by volume percent. put what ever gold and silver you have in an accurate measuring cylinder and adjust for the amount of water it displaces so that both the gold and silver displace an equal amount of water…However, you still can do it more accurately by weight by taking into account that silver has an atomic weight of 107.9 and gold is much heavier at 197 per mole… a mole of silver and gold weighs that many grams respectively…a mole of any pure element has the same number of atoms in it…one mole of gold to one mole of silver should yield your 50/50 electrum…
As a historical note, Archimedes’ principle, according to legend was solved by archemides who was given the task of non destructively testing the gold content of the king’s crown. the king had suspected that he ahd been cheated by the goldsmith by added silver…legend has it that archimedes discovered volumn displacement when he sat in a full bath tub that overflowed. when his body volume displaced the water… he ran off without a towel, naked yelling “Eureka”… that was THE eureka moment and has been ever since…

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Thanks for that - I was just reading about electrum and thought it would be interesting to try, figured I’d see if there was any info here and voila! Excellent.

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delete posts were redundant… sorry

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I forgot to add that Archimedes’ principle is Specific Gravity, important in gemstone identification… water is the reference… the weight in water versus the weight in air…