How durable are gold-colored jewelry pieces? Can you get an allergy from the coating?
I often get these questions from customers. For this article, I collected comprehensive information about gold-colored jewelry pieces. You just can't find clear information in one place on the internet, so this article can be useful for many jewelry makers. At the end of the post, I will talk about the problem I found while searching for information.
Are all gold-colored pieces of jewelry real gold on the surface?
The gold-colored surface can be made in four different ways:
1. GOLD TONE COATING – VARNISHING
The most affordable way to make gold-colored jewelry pieces. A gold-colored varnish or paint is sprayed on the surface of the metal alloy. No real gold is used in the lacquering. This is the most common way to give a gold color to base alloys.
The coating does not withstand moisture and darkens easily. There is often no information about the content, so they may cause allergies.
2. GOLD PLATING
Real gold is used for gilding and it is done by electrolysis on zinc alloy, brass, silver, titanium or surgical steel.
Gilding can be divided into three different groups depending on the thickness of the gold layer:
– flash gold plating or gold electroplating – electrolytic gilding
Gold layer min. 0.175 microns.
In reality, "gold electroplating" is often thinner - 0.01-0.03 microns. Jewelry repair companies in Finland also offer this thick coating. And many gold plated pieces from China have 0.03 micron gold plating.
– gold plating – gilding
Gold layer min. 0.5 microns.
- heavy gold plating - "heavy" gilding
Gold layer min. 2.5 microns.
This group also includes vermeil or gilded silver – vermeil gilding, which is always done on top of sterling silver.
3. GOLD-FILLED OR ROLLED GOLD – KULTA DUPLEE
Gold duplicate items contain at least 5% of gold, i.e. the gold layer is the thickest of all. The gold layer is attached to the base metal at high temperature.
4. ION PLATING (IP) – ION COATING
It is done in a vacuum, which gives the best adhesion to the coating and the surface is more durable than electrolytic gilding. It is also more ecological, because it does not generate as much waste as conventional gilding.
It should be noted that gold-colored ion plating can be more than real gold, e.g. zirconium carbon nitriding (ZrCN).
The thickness can be from one atom to millimeters.
The thickness of the ion-plated gilding of crown pieces from China is usually less than 0.03 microns. The selection of parts on the market is not large.
What is the purity of the gold in the coating?
A minimum of 10k gold is used in gold plating.
The carat number indicates the purity of the gold:
24k – 99.9% gold (stamp 999)
18k – 75% gold (stamp 750)
14k – 58.5% gold (stamp 585)
10k – 41.7% gold (stamp 417)
So there is usually a gold alloy on the surface, which also contains other metals such as silver, copper, zinc, palladium and, less often, nickel. If you have ever had a reaction to gold jewelry, but you have not been diagnosed with a gold allergy, it may be that you had a reaction to other substances in the gold alloy. In that case, you can try the purest possible gold quality.
How well does the gold layer last?
All coatings, without exception, wear off over time. How fast - depends on the thickness of the coating, the amount of use and the metal, someone has a layer of gold on top of it. For example, the non-reactive surface of surgical steel extends the life of the gilding.
For electrolytic gilding (gold electroplating), the manufacturers of crown parts give a service life of about 0.5-2 years, but it is only indicative. Mechanical wear and chemicals such as cosmetics, salt water and sweat affect the durability of the coating, so it is difficult to say how long the gold layer will actually last.
While searching for information for this article, I realized that many jewelry dealers (and even jewelers) have the same problem - while the quality of the plating is often mentioned, its thickness is almost always left out. After all, it is the essential thing whether the gold plating is 0.5 or 0.03 microns.
The country of origin of Tulihemti's gold-plated crown parts is China, and their gilding is 0.03 microns thick. Most of them are gold-plated by electrolysis and some have ion plating.
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