Choosing The Proper Jewellery Metal
Human beings have always enjoyed adorning themselves with interesting objects. Just like most things in life you will almost always get what you pay for. It's important to educate oneself before making these often expensive purchases. These days people have the option to look up information online regarding jewelry education. I have noticed that there is a lot of conflicting information out there.
I’m a goldsmith with 27 plus years of experience. I would like to set the record straight with jewelry metal choices. I will take you through some of the pros and cons.
The Most Durable metals
I've gone through pages and pages on the internet that overwhelmingly suggest that 14k yellow golds and 14k white golds are more durable than 18k or even 19k. This is impossible to be true. The reason is that lower karat metals such as 10k are susceptible to having their alloys dissolve at a much faster rate than higher karat. Alloys such as copper, silver, and nickle are also easily disolved by common household products such as clorine. Also our skin produces Nitric Oxides than turn into Nitric Acid when we sweat. Nitic acid is used to test gold as it quickly dissolves the alloys of lower karat golds. Then of course both silver and copper are further dissolved by simple oxidation - the process that makes pennies and silver turn black. Higher karat golds are not only more durable and long lasting, but these metals are often much harder than lower karats due to different alloy percentages – for example, 19k might have less copper and more of the harder nickle, and metals often behave unexpectedly when adding different alloy percentages.
What does 14 karat, 18 karat and 24 karat mean?
I’m always surprised this is not common knowledge. It is just is a simple ratio. 14 karat means that 14 parts out of 24 parts is gold. The remaining 10 parts is an alloy. 18 karat is 18 parts pure gold out of 24 parts. 24 karat gold is pure gold only.
If you have bought jewelry in a mall box store you will have heard of rhodium plating. Rhodium is a member of the platinum metals family. These are rhodium, palladium, ruthenium, osmium, iridium, and platinum. They all have similar physical and chemical properties. All 5 tend to occur together in the same mineral deposits. This incredibly white metal is not that hard on its own. It is extremely hard when the molecules are layered during the plating process. It is more than double the hardness of most golds.
Plating consists of dipping a ring or other piece of jewelry in a rhodium salts bath. The ring is charged with negative ions. Then the bath is charged with positive ions. The rhodium from the salt bath is transferred to the surface of the ring.
Thin Rhodium wears off relatively fast. We plate extra heavy during our process. Having to constantly re-rhodium plate a ring can become very expensive over the years. This can eventually out price 19k and platinum rings. It can cost from $40-$100 to re-plate rhodium plated jewelry.
Why am I telling you this?
I want you all to know why certain rings are less expensive. Rhodium can make these rings more enticing to the consumer. Are they a good buy? I have already told you that the nickel in lower karat white gold makes the gold harder. It is more brittle yet much whiter. Nickel is also known as causing possible allergies and skin irritation.
Platinum became unavailable for jewelry during WW2. Nickel white gold mixed with a bit of copper became the replacement. The resulting metal was yellowish white instead of the pure white of platinum. The extra copper made it much more ductile. It presented much fewer problems with the manufacturing and stone setting processes. The new yellowish white metal was now very ductile and easy to work.
So how to market this to the consumer?
No one wanted yellowish white gold. A thin layer of rhodium plating was the solution. This turned these rings to ultra white. All of a sudden there was a smaller chance of initial nickel allergies. This can be a problem for many people. What happens when the warranty wears out at the same time the rhodium wears off? I’m now left to explain this to many clients who come by my shop. They often complain that their three-month-old engagement ring is “turning yellow” at the bottom. This is where the rhodium has worn off.
We now must add to the cost of sizing these rings the cost of adding new rhodium. Now $40 to $100 is added to a ring resizing that would have started at $50. All of the rhodium must first be sanded off to properly re-size a ring. The ring must be then re-polished and re-rhodium plated. Having a thick rhodium plating will actually extend the life of 14k white gold.
That is all I have to say about Rhodium.
Platinum was first found by the Spaniards in their conquest of South America. They called this white metal they found “little silver” or "platina". They couldn't melt it easily because of its high melting point of 32 hundred degrees. It was virtually discarded.
Platinum is found in Russia, Alaska, Columbia, and South Africa.
Platinum is now widely used as the metal of choice in very high-end jewelry. The best properties of platinum are its natural whiteness, malleability, and durability. It shouldn't crack or wear down over time.
I have seen perfect platinum rings that are up to 100 years old. They had never been worked on to build up the claws or re-shank. Its only limitation is the relative softness of its surface. This metal scratches easily. It is tough to maintain a mirror shine. Platinum can easily be joined with solder to other precious metals.
19 karat white gold
Yes there is some nickel in 19 karat white gold. The pure gold content is at 80 percent so the nickel has very little effect as an irritant. 19k is so sought out for it's incredible durability. It has a natural whiteness that does not require rhodium plating. The alloys of 19 karat gold are somewhat of a trade secret.
Most goldsmiths don’t know the exact combination of metals.
It usually won't crack and solders well.
This metal is by far my personal favorite.
There are several jewellery brands that now sell an almost exclusively palladium and palladium alloyed jewellery.
It is relatively inexpensive and easy to shine up.
This isn’t the first time palladium was used in jewellery. It started about 50 years ago.
There are some problems with this metal while soldering or welding. I first came into contact with it years ago. It was to repair a piece that had separated. I had noticed a black soot line inside the weld. Some of the senior goldsmiths said that was why they didn’t use anymore. It oxidised quickly. A good dose of flux didn't even help.
Half of the rhodium, platinum, and palladium mined has been used in catalytic converters.
Palladium is incredibly malleable. It is also very white. This metal does not solder well and sizings may crack.
It's too soft to use in most serious jewellery construction. We wouldn't want expensive stones to fall out easily.
It is very inexpensive and great to have as fun jewellery. You don't have to worry as much about losing or damaging it.
Silver also tarnishes without a plating of some sort. Rodium plating or plastic are often used. A non-tarnishing silver alloy is now available.
It is by far the whitest metal. It solders well to other metals.
This metal has enjoyed an increasing use in men's wedding bands in recent years. It is very light-weight and non-irritating to the skin. It scratches easily but not deeply. Titanium is also relatively inexpensive.
A TIG or Laser welder is used to join the metal. It will crack fairly easily at the join with any stress. Soldering to other metals is not generally possible.
The word "tungsten" is Swedish for "heavy stone". It is a very heavy and dense material.
Tungsten also has an incredibly hard surface. One selling technique is to give the client a file and ask them to try and scratch the surface. Don't drop the ring on a hard surface because the ring just might shatter upon impact. Items that are incredibly hard are often very brittle.
Goldsmiths are generally unable to work with Tungsten carbide as far as I am aware. These rings are made though an industrial machining process.
Tungsten carbide is a non-malleable grey metal. Soldering to other metals is not generally possible. It may only be cut with a diamond saw. Stuck rings can be removed by using a special set of pliers that breaks the ring. Check with your local medical center.
I hope that you have taken something useful from my experience with these metals.