Rhodium plating - what is it? This is the name given to the process of coating jewelry made of various metals with a thin layer of rhodium. The procedure allows you to add shine to jewelry and improve the quality of products. Rhodium plating is most often used in the production of jewelry. Helps preserve white gold and highlight the shine of stones.
Gold jewelry coated with rhodium
The effect of rhodium plating on jewelry. What does rhodium plating on gold mean?
Gold is coated with a rhodium film for aesthetic reasons, as well as to give the products special properties.
Rhodium-plated yellow gold takes on a distinctive appearance, comparable to that of white gold. Moreover, the coating is applied to the base metal of any standard, starting from 585. Regardless of the original color of the noble metal - yellowish or reddish, it becomes shining with a silver-steel tint. White gold, which has a characteristic yellowish tint, acquires a perfect white color after being plated with rhodium.
Rhodium plating of jewelry
The shiny appearance of the surface with a particularly durable coating distinguishes it in appearance from the characteristics of jewelry made in the traditional way. This option for processing rings, earrings, rings, chains, and bracelets is gaining its fans. Gold rhodium plating enhances the brilliance and beauty of precious stones.
Placing rhodium on the base of a white or clear stone, such as a diamond, visually increases its size. In addition to design properties, products acquire qualities that increase their safety for a long time.
Purposes of rhodium plating gold
By applying rhodium plating, the surface of jewelry becomes durable and not subject to deformation, scratches or small cracks. Similarly with silver: rhodium-plated products are protected from oxidation and the appearance of a characteristic black coating, retain their shine, and do not tarnish.
The main areas of use of rhodium plating:
- giving a certain shade to jewelry;
- processing of places where precious stones or other design elements are inserted;
- The technological feature of the coating is the strengthening of the fastener, which is most susceptible to deformation and wear.
Historical facts
Rhodium was discovered in 1803; it was obtained by studying platinum, which most often includes this metal. Rhodium acts as an auxiliary element, and it is considered the most expensive among natural metals.
In Russia, this element was not used for a long time; it was sold for next to nothing to Europe or was completely thrown into waste, considered useless.
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Only during Soviet times was an institute created to study the properties of noble metals. Scientists have finally managed to study rhodium and obtain information about its properties.
Rhodium belongs to the group of platinoids. Rhodium plating has the following properties:
- Not susceptible to aggressive acids and alkalis.
- Gives the product strength and durability.
It is worth noting that rhodium was not always used to give jewelry its shine and characteristic whiteness. Gold was mixed with nickel, and rhodium was added to the alloy, wanting to reduce the cost of production.
The experiments ended with a large number of people being harmed by the decorations. The reason is that nickel causes allergies. After an unsuccessful experiment, we remembered rhodium, which does not cause allergies and helps give gold its characteristic white color and shine. The use of this metal in the composition of the ligature led to the fact that the cost of jewelry increased sharply.
Rhodium was discovered by an unremarkable doctor: William Wollaston, this discovery made the scientist rich and famous. But in essence, he simply tried to dissolve the metal in acid.
Pros and cons of this procedure
Gold products coated with a layer of rhodium film are characterized by increased wear resistance and less susceptibility to atmospheric influences, such as temperature. The hardness of the material increases, since gold in its pure form is a rather soft, ductile metal that is easily deformed.
Attention! This also applies to antique jewelry. To make them last longer, you can rhodium plate them in a jewelry workshop.
Despite its positive qualities, the rhodium surface can still gradually wear off over time, so caring for jewelry requires care and attention. You can extend the time when the decoration pleases the eye by following simple rules:
- wear jewelry carefully, because the coating layer is very thin;
- avoid conditions of high humidity and potential contact with chemicals;
- Store in a protected place and periodically wipe with a soft cloth.
Rhodium-plated products cannot be soldered; to change the size of the ring, you will have to remove a layer of metal.
In addition, the disadvantage is the inability to determine by eye what kind of metal is in front of us. In traditional gold processing, an experienced jeweler or even an experienced amateur determines the purity and quality by its appearance.
Price
The cost of rhodium is many times higher than the price of gold, but this not only does not reduce the demand for it, but every year it increases many times over. Rhodium plating can be done in any specialized jewelry workshop. When applied to equipment, the shine will disappear, but chemical resistance to oxidative processes will remain, and abrasion resistance will also increase.
The price of rhodium-plated gold jewelry depends on the following factors:
- Raw material.
- Rhodium plating methods (immersion, selective).
- What area is the coating applied to?
- Thickness of the protective layer.
- The current cost of rhodium in the workshop, which depends on the economic situation on the world market.
Interesting! At one rhodium processing factory there was a mortar that weighed thirty kilograms. The appearance was ordinary and simple, but the cost exceeded the price of the entire plant, since the material for making the mortar was rhodium.
Rhodium plating technology using electrolysis
The most common method of coating jewelry with rhodium film is galvanic, or electrolysis. This is a physical and chemical method that involves the use of the principle of concentration of substances present in a certain solution on electrodes. The process takes place under the influence of electric current.
The technology involves several stages.
Electrolysis of melts and solutions
Step 1: Degreasing and rinsing in various solutions
The preparatory stage comes down to bringing the jewelry to a state that is most suitable for electroplating - coating the metal with a layer of another metal.
At this stage:
- The decoration is cleaned. For this purpose, special solutions can be used.
- Degreasing is carried out using alkaline solutions.
- Rinse several times with hot and then cold water.
- They are kept for a short time, just a few seconds, in hydrochloric acid to increase the adhesive properties of the precious metal.
Adhesion is the property of dissimilar substances to stick to each other due to intermolecular interaction.
The particles penetrate each other, holding the materials together. This is called surface activation.
Having carried out these preparatory procedures, you can be confident in the further success of the galvanic process.
The nuances of processing colored gold with rhodium
In jewelry, non-ferrous gold refers to any type of precious metal that differs significantly from pure gold. This is determined by the impurities that are added to the gold alloys. 100% gold is defined as 24 karat gold, divided schematically into 24 parts.
Additions of copper, silver, nickel, palladium and other metals change the color of gold towards reddish shades, yellow, green or white.
Red gold, often used in work, is 18-karat, containing 75% gold, 25% copper. Pink -18 karat: 75% gold, 22.5% (20%) copper, 2.75% (5%) silver. There is yellow, green, purple, blue, black gold. Black is one of the types directly related to rhodium, although there are other technologies for producing a precious metal of such an unusual color.
When working with colored gold, and this is most often a red and yellow noble metal of standard standards, rhodium plating is carried out not over the entire surface, but at the locations of design elements. Precious and semi-precious stones are most often used. The bed where they are placed is processed.
It is important! White gold, which has a characteristic yellowish tint, acquires a perfect white color after plating with rhodium.
Rhodium-plated gold ring
Rhodium colors
The original color of rhodium is silvery white with a low sheen. Experts call this color bluish-white. The compounds are most often dark red in color, which is how it got its name in ancient Greek.
Types of gold processing with rhodium
The main methods for producing rhodium-plated gold are: immersion and selective. The products are immersed in a solution of rhodium salts, then they are completely covered with a film. Part of the jewelry is processed, for example, the bed under the precious stones - this is a selective method.
Along with this, we can talk about the use of various solutions that provide two types of rhodium treatment:
- Regular, white rhodium plated.
- Black rhodium plating.
Regular rhodium plating for cool shine and silver tone
With the usual method of processing rhodium, products acquire a silvery-white color with a coolish tint.
Black rhodium plated and antique look
Black rhodium plating can be applied to the entire piece of jewelry or to individual parts of the surface. If the decoration has a complex shape, the black layer is deposited unevenly by electrolysis. That's why it begins to resemble ancient rings, rings, and earrings. Applicable primarily to products with dark or black stones.
Rhodium plating can be not only white but also black
Differences between rhodium plated silver and regular silver
This metal has common external features with white gold and platinum. Rhodium plated silver differs from conventional products in a number of ways:
- Visual effect. Rhodium-plated silver is characterized by a specific shine and bright shine in the rays of light. Pure metal does not shine and has a tint of gray.
- Rhodinated silver differs from sterling or pure silver in its even color and special ductility due to the copper in its composition. The rate of its oxidation depends on the mass fraction of copper and the type of skin of the owner.
- Oxidized silver is pre-treated with a sulfur solution until a thin oxide film is obtained. The convex parts of the jewelry are polished, giving the effect of artificial aging. This is how it differs from rhodium-plated elements.
- Blackened silver contains some lead and sulfur. The alloy has an even color, but unlike rhodium-plated areas it does not shine.
As you can see, rhodium plated silver compares favorably with other types of processing. For this reason, even leading fashion jewelry manufacturers such as Tiffany & Co, Christian Dior and Gucci produce separate collections that exclusively include rhodium-plated silver items.
If you have the slightest doubt regarding the type of coating, we recommend contacting an experienced specialist. Rhodium-plated silver costs much less than gold or platinum, which is often used by unscrupulous jewelers.
Rhodium plating of gold jewelry. Regular care of rhodium plated jewelry
Caring for rhodium-plated gold involves following simple rules
- Store products in a special box or case.
- Clean and polish products using soft cloths and brushes.
- Protect them from contact with a damp environment and from contact with chemical reagents.
- Wear jewelry during the day, removing it at night and before applying cosmetics.
- When the rhodium layer wears off, you can take it to a workshop to renew it.
Difference from other metals
Rhodium plated silver is quite difficult to distinguish from other metals. The greatest external similarity of this material is observed with platinum and white gold. In order to accurately determine the type of coating, it is necessary to take into account the main characteristics. Among them the following stand out:
- Any other metal will be significantly inferior to rhodium-plated silver in terms of shine. If you need to determine the material of an unprocessed product, then you should look for the desired one by the gray or light black tint of the surface.
- To find differences from white gold, a visual inspection of the jewelry should be carried out. It will help determine the metal sample and the shape of the marks, which differ for each material.
- Rhodium-plated silver differs from platinum in the same ways as white gold.
If the buyer of jewelry is not a professional, then the work of determining the type of material should be entrusted to a highly qualified specialist. Based on experience, he will carry out the necessary manipulations and make his verdict. This option, although expensive, allows you to reduce the likelihood of error to a minimum.
To determine which rhodium plated silver is best, you need to understand the properties and characteristics of each. This is also a rather difficult task that only professionals can handle.
Category: question-answer
Doesn't rhodium plating make gold cheaper?
Expert opinion
Pribrezhny Gennady Valentinovich
Jeweler 6th category
Rhodium is more than 10 times more expensive than gold. Therefore, a product coated with this metal is only more expensive.
How much does rhodium treatment cost in Moscow very urgently?
Expert opinion
Grishanov Mikhail Petrovich
Jeweler, director of the Grishanov and Co. workshop
If the rhodium layer is applied for the first time, it costs several hundred rubles. Replating a white gold ring in Moscow or Chelyabinsk costs up to several thousand rubles. The cost varies depending on the area covered or the weight of the jewelry. If rhodium plating is urgently needed, this also affects the price.
How often should the rhodium procedure be repeated?
Expert opinion
Pribrezhny Gennady Valentinovich
Jeweler 6th category
The re-spraying procedure is carried out differently for different products. It depends on the conditions under which the jewelry is worn and stored. The gold standard has a certain influence on the duration of preservation of the layer; for non-ferrous types of metal it is shorter. The coating of chains and pendants is renewed once every year and a half, this depends on the thickness of the layer. The coating on rings lasts up to 3 years, and on earrings and brooches - up to 7-10 years.
Rhodium-plated gold
Why is white gold plated with rhodium?
Expert opinion
Grishanov Mikhail Petrovich
Jeweler, director of the Grishanov and Co. workshop
White gold has a characteristic yellowish tint. When rhodium plating is carried out, it acquires a perfect white color.
