If the high-end jewelery and watches sector is characterized by one thing, it is by offering its customers a premium product that uses materials of excellent quality. These materials include precious metals such as, for example, gold, silver, platinum, or palladium, among others.
The use of these materials implies a very high quality control, almost perfect, since each piece is worth its weight in gold (pun intended). For this reason, it is crucial to detect and know the problems that can occur during the manufacture of this type of products to give them a quick and efficient solution, thus avoiding the waste of this type of materials whose price is very high.
In addition, due to the price of high-end jewelery and watches, the expectations of the end customer are very high. For this reason, these types of products cannot afford the luxury of initial quality failures, or during their use.
In today’s blog we tell you about our experience with this type of forensic engineering projects applied to jewelry and watches, the defects and failures that we have faced and, of course, what has been our solution in each of them, there go.
If there is a product that cannot be allowed to fail, it is a jewel or a high-end watch. These products are carefully checked before and after your purchase. For this reason, any failure that appears is a big problem for the manufacturer and must be resolved quickly so that it does not occur again. The most common failures in this type of product are:
The formation of cracks in precious metals is one of the most common jewelry and watchmaking failures in their manufacture. Being visible cracks on the surface, they are easily detectable when they appear, however, these cracks can appear after months of use of the product. Therefore, the main problem that these types of cracks present is their unknown origin.
The surface defects of metallic products are often related to the formation of oxides. These oxides, which can be produced both on the surface and inside, considerably affect the aesthetic appearance of the product and its physical properties. To know the resistance of a metal to oxidation, it is very useful to do comparative tests in potentiostat. We leave you a link to our corrosion testing blog.
In products containing nickel alloys, both in surface layers and internal layers, the release of nickel can occur. This phenomenon, characteristic of 1 and 2 euro coins, occurs due to the contact of nickel alloys with skin sweat. Nickel release may not be visible to the naked eye, however it creates significant skin allergy problems for users. In future blogs we will tell you more about this topic, which is increasingly important in jewelry and costume jewelery.
Products that contain connecting pieces may present breakage problems that affect the entire product. This rupture occurs as a consequence of a previous failure, such as internal defects in the metal or impurities. To solve this type of problem it is very important to characterize the broken part and detect the origin.
Shine is one of the most important aesthetic properties in the metals that make up jewelry or watches. The loss of this property greatly influences the quality of the product. Knowing the reason why it occurs is very important in order to find a correct solution.
In addition to these failures, we can find other types of problems. Therefore, it is advisable to study each case separately to find the best possible solution, especially if we work with materials that have such high costs.
All the above-mentioned failures have an origin. Knowing the origin of the failure is the first step to give a correct solution. Next, we present some of the main reasons why the failures that we have anticipated occur.
As in any other sector, the quality of the materials with which one works is essential to achieve a good finish of the product. In the case of jewelery and watches, the presence of impurities can cause major oxidation, aesthetic or even mechanical problems. If the impurity is on the surface it can be detected more easily, however, if the impurity is in the internal layers of the product it is more complex. To detect impurities in ATRIA we can characterize the composition of the metals that form the product very precisely, using ICP-MS (Inductively Coupled Plasma Mass Spectrometry).
Many jewelry products contain several layers of different metals or alloys, the deposition of which must be perfect so as not to generate aesthetic, mechanical or any other type of problems. Detecting if the correct layer thickness has been deposited or if it contains micro defects is a very complicated task, since it is found in the intermediate layers and requires a lot of precision in the analysis.
To carry out this characterization, at ATRIA we used an electron beam scanning electron microscope (FIBSEM). In the image you can see a test carried out on a piece with different layers of metal. Once the problem has been detected, it is possible to correct the deposition parameters of the metallic layers to avoid this type of jewelry failure.
As in the previous case, an internal crack, or the presence of pores, can lead to significant problems during the use of the product. For this reason, it is important to know if jewelry failures that are occurring are due to the presence of microcracks or micropores inside the product. In this way, it is possible to act on production and avoid the manufacture of new products with microcracks.
In some cases, the presence of incompatible metals can lead to accelerated corrosion processes, since ions pass from one metal to another during prolonged exposure to sweat. In addition to corrosion, this incompatibility of metals can lead to the release of nickel, generating significant allergies in the users of the product.
If paint is used to cover some areas of the metal, the loss of paint thickness in some areas of the piece can cause aesthetic problems and loss of protection. In the case that the paint offers a protective function, it is very important to detect the areas where the adequate thickness is not being deposited, in addition to evaluating whether the adhesion is correct.
The high roughness of a metal surface greatly affects gloss. For this reason, a localized loss of gloss may be due to a slight increase in the roughness of that area. Characterizing it is the first step in solving the problem.
Our forensic engineering team has faced the challenge of finding the source of failure in many jewelry, watch and similar products. Here are some examples:
In this project, the jewelry product was made up of several metallic layers. Specifically, the lower layers contained nickel, which was protected with other more superficial layers of gold, palladium or paint, among other options. The problem with this product is that, in contact with sweat, it led to the release of nickel. This should not happen since there were several layers protecting the nickel on the surface. After analyzing the failure with various techniques, the origin of the problem could be detected by FIBSEM characterization. The cross section of the piece allowed us to know the reason why the sweat from the skin came into contact with the nickel of the lower layers. Thanks to this, a modification of the production process was proposed to avoid this phenomenon.
In this case, a specific area of the metal part lost its shine, which affected the aesthetic appearance of the product. Our client was unaware of the reason for the loss of gloss. To solve the problem, we physically and chemically characterized several samples of the production process until we understood which ones showed loss of gloss. By relating this information to the process parameters, it was possible to solve the problem, which in this case came from a product cleaning bath.
In this case, our client had problems in his production process and wanted to make sure of the thickness of all the deposited layers. Furthermore, he wanted to confirm that there were no internal defects between them (micropores or microcracks). For this, we made a FIBSEM analysis of several samples of the same process, in this way the reproducibility of the pieces was ensured.
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