Pure gold is not (often) used in jewelry, and even when it’s used, the resultant 24k gold jewelry is quite soft and at high risk of damage. The 24k gold jewelry is bent easily, it scuffs, and it will also have many scratch marks if you wear it frequently. So, unless you are planning to invest in the 24k gold jewelry just for investment, this karat gold might not be the best option for you. Keep in mind that there is also the risk of the gold jewelry being snatched off you – that, and the fact that 24k gold doesn’t really look good as jewelry – it is too bright yellow and almost looks orange, which isn’t what you are looking for.
So, to remedy this, the pure gold is mixed with other metals that not only create nicer gold color but also make the gold a lot more durable, strong, and therefore able to withstand daily wear.
In this article, we’ll share insights into the specific metals that are added to pure gold to make it harder, durable, and stronger. Keep reading!
Why is 24k Gold too soft? What is the Mohs Scale of pure gold?
As mentioned above, pure gold or 24k gold is too soft, which is why it is NOT the most common choice of metal for anyone looking for more durable jewelry.
The reason for the softness and malleability of gold has to do with the fact that pure gold is a precious metal whose molecules are packed loosely (or considerably loosely than most other metals and minerals). As a result of its molecular structure, 24k gold is less dense, soft, and it’s also comparably soft on the hardness scale called the Mohs scale. This scale measures how easily minerals are scratched in relation to other minerals on earth, and from the research carried out, pure gold is quite soft, scoring a mere 2.5 on this 0-10 scale of mineral hardness – talc is among the softest minerals on earth, while diamond is ranked 10 as it is one of the hardest things on earth.
Confused or wondering just how hard gold is since it scores a 2.5? Well, the hardness of gold can be equated to the hardness of your fingernail, which, as you can tell, isn’t really that hard, and it can be bent and damaged quite easily.
However, when the pure gold is mixed with other metals, its level of hardness jumps to between 3.5 and 4, which then puts the solid gold alloys in the same hardness level as platinum and a few other ‘harder’ metals. That said, even in its alloyed form and at a score that is quite close to that of platinum, platinum would still be harder than gold because it is much denser than gold.
That said, it’s important to keep in mind that the Mohs scale of hardness will not tell you how the metal in question would react to harder metals when it comes in contact with them.
Why some metals mixed with gold to make it harder?
Though very malleable, gold is also quite ductile in its pure form, which is why pure gold is often used in electronics where it’s used as a bonding wire. Unfortunately, this quality cannot be used in jewelry, and the gold has to be hardened. Adding other metals to gold is essential because the best gold jewelry must withstand constant wear and also be stylish and versatile. These qualities are seen in gold only after it’s alloyed.
In addition to hardening gold, different metals are alloyed with pure gold in different proportions to bleach out the color of pure gold. Pure gold is bright yellow and too soft, two qualities that are not desirable in the best kinds of jewelry. With this in mind, gold has to be bleached to create more desirable colors and a more durable version of gold.
So, why use some metals and not others?
Metallurgy – the main reason why metals like copper are used to bleach and harden pure gold is because of the metallurgical properties of that metal. When these metals are added to pure gold, the karatage of gold is reduced, and the melting point of the alloy is also lowered. Metals like copper will increase the strength of the gold, making it less ductile and easier to use in jewelry making.
Reduced ductility and malleability – this is the other reason for the addition of these metal alloys; they alter the physical properties of pure gold by reducing its ductility and malleability. Alloying pure gold with silver, for example, reduces the malleability and the ductility of gold because silver atoms are smaller than the gold atoms, meaning that the silver atoms have a stronger effect in increasing the hardness and the level of strength of gold through the distortion of gold’s crystal lattice. This also results in the reduction of the karatage of gold, with the lower kararage gold alloys being stronger and harder.
Harder versions of gold equal more desirable jewelry – anyone looking for good quality jewelry is always looking out for more durable jewelry that will look good for a long time, making the price tag worthy. With this in mind, jewelers alloy pure gold with different metals to create alloys that are stronger and more ideal for creating durable jewelry.
What metal is mixed with gold to make it harder?
1.Copper– this is the primary metal added to gold to make it harder and more durable. Copper added to pure silver not only makes the gold redder but also reduced its karatage and makes it denser by strengthening the molecular/ lattice structure of gold. The metallurgical properties of copper also enhances the durability of gold, hence its use in making gold alloys. Copper is behind rose gold.
2.Silver– This is one of the metals that are added to pure gold to bleach the gold. Besides the color change and the creation of yellow gold, silver is quite effective in reducing the ductility and the malleability of pure gold, making it harder and more durable/ stronger through the distortion of the original gold crystal lattice, creating a lower karat gold, but also a version of gold that is harder.
3.Zinc– zinc is considered a moderate bleacher for gold, but it’s often used in place of the allergy-flaring nickel in the creation of white gold. Zinc also hardens gold.
4.Palladium is also used often because it boasts stronger bleaching effects while also strengthening the pure gold as it lowers its karatage.
5.Nickel, though a less desirable metal, because it’s behind most skin sensitivity reactions and allergies, boasts powerful bleaching effects on gold, which is why some jewelers still use it. It’s also quite affordable.
Composition of Gold Alloys in Colored Gold Jewelry
Check the picture bellow
|Color of Gold||Composition of the gold alloy|
|22k Yellow gold||91.67% Gold/ 5% Silver/ 2% Copper/ 1.33% Zinc|
|18K Red Gold||75% Gold/ 25% Copper|
|18K Rose Gold||75% Gold/ 22.25% Copper/ 2.75% Silver|
|18K Pink Gold||75% Gold/ 20% Copper/ 5% Silver|
|18K White Gold||75% Gold/ 10% Palladium/ 10% Nickel/ 5% Zinc|
75% Gold/ 25% Platinum or Palladium
|18K Gray-White Gold||75% Gold/ 17% Iron/ 8% Copper|
|18K Soft Green Gold||75% Gold/ 25% Silver|
|18K Light Green Gold||75% Gold/ 23% Copper/ 2% Cadmium|
|18K Green Gold||75% Gold/ 20% Silver/ 5% Copper|
|18K Deep Green Gold||75% Gold/ 15% Silver/ 6% Copper/ 4% Cadmium|
|18K Blue/ Blue-White Gold||75% Gold/ 25% Iron|
|Purple Gold||80% Gold/ 20% Aluminum|
If you weren’t sure about metals added to gold to make pure gold harder and why these metals were chosen, we hope that this article answers your questions. Keep in mind that the metals added to gold will determine the type of gold that is formed, and its color.