By Alexandra Porto
If you’ve ever owned a solid gold chain or timepiece, you know the heft of its price is often only matched by the heaviness of the piece. Generally, such solid and substantive weight is the primary indicator that the jewelry piece in question is in fact real gold.
In the future, this may no longer be the case. Imagine a watch or jewelry piece with all the purity of 18-karat gold but at only a fraction of its weight. For women who enjoy wearing gold earrings but are discomforted by their ears being pulled, or for those who avoid wearing heavy necklaces that weigh them down, this innovation in gold material could be a dream come true. Soon, they could have their proverbial cake and eat it too with a new option to wear gold that is as comfortable as it is luminous.
A team of scientists at the Swiss university ETH Zurich is hard at work turning that dream into reality. Material scientist and ETH Lab head Raffaele Mezzenga is convinced that this new gold will be ideal for creating jewelry or timepieces and is likely to attract strong interest from jewelry companies due to its unique properties that provide enhanced comfortability.
A new lightweight gold could make heavy timepieces a thing of the past.
Photo Credit: johnshelley120 (pixabay.com)
Scientists Have Created a New Lightweight Gold
After years of studying alloys with the goal of creating a new lighter form of gold, the team of Swiss researchers at ETH Zurich, being led by Leonie van 't Hag, has made a significant breakthrough. Their newly developed material has the same glistening properties of 18-karat gold but at an incredibly lighter weight that is only one-fifth to one-tenth that of normal 18-karat gold.
Typically, 18-karat gold is composed of 75 percent gold and 25 percent silver or copper. According to the journal Advanced Functional Materials, ETH Zurich replaced the 25 percent metal component with protein fibers and a polymer latex to create this new material. Using this method allows for an 18-karat gold that has an equivalent purity to traditional pieces but only weighs 1.7 grams per cubic centimeter rather than a conventional 15 grams per cubic centimeter.
Its lightweight properties make it feel like aluminum, but with the composition of 18-karat gold. It even maintains the look of traditional gold with the same metallic luster you expect to see from this valuable metal. On the ETH Zurich website, Peter Rüegg echoes Mezzenga’s belief that “lovers of gold watches and heavy jewelry will be thrilled. The objects of their desire may someday become much lighter, but without losing any of their glitters. Especially with watches, a small amount of weight can make all the difference.”
ETH Zurich’s past development of gold so light it could float on milk foam.
Photo Credit: Gustav Nyström and Raffaele Mezzenga / ETH Zurich
It All Started with Gold Foam
The discovery of a molecularly lightweight gold that maintains all of its outward physical properties didn’t happen overnight. This initiative has taken years of research and builds upon a past study spearheaded by Mezzenga chronicled in the journal Advanced Materials on Nov. 23, 2015. At that time, he developed a different type of “new gold” that was even lighter than this most recent development. In fact, this original experimental gold was so lightweight that it was described as a “gold foam.”
That original study of gold material produced the lightest gold nugget ever created. Weighing one thousand times lighter than conventional 20-karat gold, Mezzenga described it as “lighter than water and almost as light as air.” It was so light, that when placed in the frothy milk of cappuccino it literally floated on the foam.
This “gold foam” was created by heating proteins and converting them into tiny fibers called amyloid fibrils. These tiny fibers were then added to a gold salty solution and interlaced into a porous three-dimensional mesh. That mesh was made up of gold nanoparticles and microcrystals with unique catalytic, pressure-sensing, and autofluorescent properties.
This molecular combination resulted in an aerogel structure which was then dried and converted into a foam. Like their latest creation, this experimental “gold foam” also maintained its usual metallic shine despite the innovative process and structure.
Unfortunately, this early innovation was limited as the “gold foam” proved to be too unstable for any usable, real-world application. The problem of physical stability is due to its structure being made up of 98 parts air and only two parts solid material.
The experimental “gold foam” proved to be too soft and malleable to be used in jewelry or any other products that rely on a solid molecular structure. However, the porous matrix created proved to be vitally useful in developing and ensuring the functionality of ETH Zurich’s newest lightweight gold.
This Lightweight Gold Contains Numerous Air Pockets Invisible to the Eye.
According to Kitco News, “to create the new form of gold, researchers said they combined the gold with the protein fibers and a polymer latex. Water is used to create a dispersion. Alcohol replaces the water to turn the dispersion into a gel. The alcohol gel is then put into a pressure chamber and pumped with CO2 which enables the miscibility of the alcohol.”
Developed in a similar fashion as their original “gold foam” experiment, the Swiss research team combined protein fibers and a polymer latex into a matrix. According to Slash Gear, “nanocrystals of gold were embedded as thin discs within the aforementioned plastic matrix, causing many invisible pockets of air that cut down the density and the weight.” These tiny air pockets within this matrix are the key to the lightweight properties of this new alloy.
Mezzenga went on to explain that their lightweight gold has attributes similar to plastic but remains in line with the desired properties and expectations of conventional gold. “If a piece of it falls onto a hard surface, it sounds like plastic. But it glimmers like metallic gold and can be polished and worked into the desired form,” said Mezzenga. The ETH Zurich team even posted a video on YouTube where you can hear the gold fall onto a surface and it, without a doubt, sounds like plastic.
Peter Rüegg, head of corporate communications at ETH, said the composition of the gold can be further tweaked by applying heat afterward to the plastic polymers, transforming it into the desired shape while still preserving its gold composition.
While this new gold shows great promise, there is one little-discussed downside. JKC Online reports that when asked if this new gold has the same durability as traditional 18-karat gold, Mezzenga said researchers can’t say for sure. “My naive answer would be no,” he says. “Gold is gold. It’s perpetual. Plastics are long term, but I wouldn’t compare the durability of plastic [to] that of gold.”
This new lightweight gold could be used for other applications, such as electronics.
Photo Credit: Gosia K, Pixabay
This Can Be Useful for Applications Beyond Jewelry
The team has applied for patents on this unique process and the new lightweight gold they have created. Right now, Mezzenga seems focused on the marketing appeal of this new gold to watch and jewelry manufacturers but mentioned that there are several other applications for this unique alloy.
Given it’s lightweight, it could be very useful in medical and technology fields for radiation shielding, electronic parts, or chemical catalysis.
One of its greatest features, which would also prove helpful to manufacturers, is that it is believed to be easier to work with than conventional gold. Its melting point is only 221 degrees Fahrenheit as opposed to the 1,943 degrees Fahrenheit it takes to melt traditional 18-karat gold.
This new alloy will allow gold to come in a wide range of custom hues.
Photo Credit: Andrea Stöckel, Public Domain
Custom Colored Gold is Now Possible
This new gold also allows for greater flexibility as its hardness and color can be adjusted. By slightly altering its composition, say from latex to another plastic like polypropylene, you would be able to even create gold in a custom hue such as violet or dark red. Mezzenga told Phys.org, "as a general rule, our approach lets us create almost any kind of gold we choose, in line with the desired properties.”
According to Dogo News, “it is also possible to vary the color by swapping the shape of the gold nanoparticles inside the matrix. For example, irregularly shaped nanoplatelets will produce the conventional yellow shimmer, while spherical nanoparticles will result in gold with a violet hue.”
This could really be game-changing for manufacturers looking to add unique flair and creativity to their jewelry lines. However, skeptics believe this could take some time before it hits the market as consumers would need to adapt and learn to separate the weight of gold from its attributed value.
The team at ETH Zurich is leading the charge in revolutionizing this highly sought metal in unconventional ways. Whatever the future of gold holds, it’ll be interesting to see how this team continues to push the boundaries of material development, while challenging us to reconsider notions of what is real gold.