Gold is one of the most valuable and coveted metals, known for its beautiful yellow color. Throughout history, gold has been highly prized for making jewelry, coins, and more. But pure gold is very soft, so it is often mixed with other metals to increase its hardness and durability.
Alloying Gold
The process of mixing metals is called alloying. When gold is alloyed with other metals, the resulting mixture is called gold alloy. Some of the most common metals used to make gold alloys are silver, copper, palladium, and zinc.
Gold can be alloyed with silver, copper, or both to create different colored gold alloys. Here is a look at some of the most popular gold alloys and how they differ from pure gold:
| Alloy | Gold Content | Other Metals | Color | Properties |
|---|---|---|---|---|
| Yellow Gold | 75% | Silver & Copper | Yellow | More durable than pure gold |
| White Gold | 75% | Silver, Copper & Palladium | Silver-white | More scratch resistant than yellow gold |
| Rose Gold | 75% | Copper & Silver | Pinkish hue | Durable, does not tarnish |
| Green Gold | 75% | Silver & Zinc | Light green | Durable, unique color |
Why Add Silver or Copper to Gold?
Silver and copper are the two most commonly used metals for alloying with gold. Here are some of the key reasons they are added:
- Hardness – Pure gold is very soft. Silver and copper make gold alloys harder and more durable for jewelry and other uses.
- Color – Silver creates a pale yellow or white color. Copper creates a rose or reddish hue. The mixture of silver & copper alters the color.
- Affordability – Alloying gold with cheaper metals like silver & copper reduces the cost compared to pure gold.
- Workability – The addition of other metals makes gold alloys easier to work with for manufacturing jewelry and other items.
- Tarnish Resistance – Silver and copper help prevent gold from tarnishing and oxidation over time.
In short, adding silver or copper creates gold alloys that are more durable, affordable, and workable than pure soft gold. The mixture also allows creating different gold colors for jewelry and decorative uses.
Silver Alloys
Here is a more in-depth look at gold alloys made with silver:
- White Gold – The most common white gold alloy consists of 75% gold, 16% silver, 5% copper and 4% palladium. The high silver content gives white gold its bright white color.
- Green Gold – Green gold gets its color from having a high silver content ranging from 20-45%. The remaining portion contains 75% gold and sometimes a little copper.
- Rose Gold – While copper plays the biggest role in creating rose gold, silver can also be present from 2.5-20% to deepen the rosy pink shades.
- Yellow Gold – Silver is added to yellow gold in smaller amounts around 5-20% to add hardness without altering the golden color significantly.
The key takeaway is that silver is essential for achieving white gold alloys. It also helps create unique green gold. In rose and yellow gold alloys, silver serves to enhance hardness and durability.
Copper Alloys
Here are some details on gold alloyed with copper:
- Rose Gold – Rose gold gets its distinctive pinkish hue from having a high copper content ranging from 20-24%. The remaining 75-80% is gold.
- Yellow Gold – Copper makes up 5-35% of most yellow gold alloys. It enhances the yellow color and improves hardness.
- White Gold – While less copper is used compared to silver or palladium in white gold, around 5% copper is still added to increase hardness.
- Blue Gold – A gold-copper alloy with 20-35% copper results in a bluish purple color. Less than 20% copper creates pale yellow or greenish hues.
In summary, copper is essential for rose gold coloring. It also fortifies yellow gold. Small amounts of copper complement and strengthen white and green gold alloys.
Gold-Silver-Copper Alloys
Many gold alloys contain a mixture of silver and copper together, such as:
- Yellow Gold – Most yellow gold contains 40-70% gold, 15-35% silver, and 5-35% copper. The blend of silver and copper enhances the yellow color.
- White Gold – White gold commonly contains over 50% gold, 16-34% silver, 5-24% copper, and 2-18% palladium for a white appearance.
- Rose Gold – Standard rose gold has 75% gold, 20% copper, and 5% silver. The high copper content gives rose gold its signature pink tone.
Again, the key takeaway is that careful control of the silver and copper percentages in gold alloys allows creating customizable colors from yellow to white to rose.
How Gold Alloy Composition Affects Properties
Adjusting the percentages of metals like silver and copper in gold alloys results in different material properties. Here’s a look at how gold alloy composition affects important qualities:
| Alloy Composition | Hardness | Malleability | Durability |
|---|---|---|---|
| Higher gold purity (99%+ gold) |
Very soft | Excellent | Poor |
| 18k gold (75% gold) |
Harder than pure gold | Good | Better than pure gold |
| 14k gold (58% gold) |
Much harder than 18k | Lower than 18k | Excellent |
| High silver or copper | Increases hardness | Reduces malleability | Improves durability |
The key takeaway from the table is that increasing silver or copper content makes gold alloys harder but less malleable. It improves durability for jewelry and other uses. Lower gold purity like 14k has the most hardness while high purity 99% gold is extremely soft and malleable.
Uses of Silver & Copper Gold Alloys
Here are some of the most common uses of gold alloys with silver and copper content:
- Jewelry – Different colored gold alloys are used extensively for rings, necklaces, bracelets, earrings, and more. Yellow, white and rose gold alloys are especially popular.
- Watches & Smartwatches – Gold alloys provide an attractive and durable material for watch cases and bands.
- Dental Fillings – White gold alloys are commonly used for inlays, crowns, bridges and other dental restorations.
- Electronics – Gold-silver and gold-copper alloys can be found in electronics for conductivity, corrosion resistance, and durability.
- Coins & Medals – Gold coins, Olympic medals, and commemorative items often contain silver, copper and other metals.
- Investment Gold – Gold bullion bars and coins aimed at investors are made from hardier gold alloys.
In short, gold-silver and gold-copper alloys see widespread use in jewelry, dentistry, electronics, commemorative coins, and investment gold products.
Pros and Cons of Gold Alloys
Below is a summary of the key pros and cons of alloying gold with silver, copper and other metals compared to pure gold:
| Pros | Cons |
|---|---|
|
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In summary, alloying offers benefits like better durability and workability. But it comes at the cost of lower purity and value compared to pure 24k gold. Those with silver or copper allergies may also react to gold alloys containing those metals.
Conclusion
Gold is frequently alloyed with metals like silver and copper to create different colored gold alloys with enhanced hardness. Silver is key for achieving white gold, while high copper content creates rose gold. Combinations of these metals produce yellow, green, and other gold hues.
Carefully controlling the percentages of metals like silver and copper allows tailoring gold alloy properties like hardness, malleability and durability. Higher purity gold alloys are softer and more malleable. Lower purity gold alloys are harder and more durable.
Gold-silver and gold-copper alloys are extensively used for jewelry, dentistry, electronics, commemorative coins, investment bullion, and more. While alloying does reduce gold’s purity and value, it creates more affordable and durable gold materials.
In summary, silver and copper are both commonly mixed with gold, either separately or together in a blend. This alloying process is essential for creating specialized gold materials with colors spanning yellow, rose, white, green, and more for a wide variety of applications and uses.
