Solid silver object usually bear hallmarks to testify the silver fineness of the metal. In most cases, also silverplate items, besides the manufacturer's trademark, present well known abbreviations or names to distinguish the metal used in the plating process (EPNS, EPBM, Métal Blanc, Alpaka, etc.).
This is the norm, but what to do when we find a piece unmarked or with a "fantasy" or unknown mark? How to distinguish solid silver from silverplate?

Silverplate is the term commonly used to identify an object made of base metal (white metal, bronze, copper, etc.) on which a thin layer of silver was transferred by a process of electro deposition. The silver coat is extremely thin and rarely exceeds 50 microns (5 hundredths of a millimetre). Often, the repeated use and the cleaning remove the thin layer of silver bringing to light the underlying metal (particularly in the protruding parts of the piece). Obviously, in this case, to identify the metal as silverplate is a simple task.

Otherwise, you can use one of the chemical reagents available on the market to test the silver quality.
It consists of a strong acid (nitric or sulphuric acid) mixed in appropriate proportions with a solution of potassium dichromate.
A drop of this yellow color reagent, placed on a silver surface, causes a chemical reaction of bright red color (silver chromate).
This reaction happens only when the surface is solid silver. The reagent can not detect the fineness; pure silver (999%) and its alloys (925, 800) react at about the same way (only slight differences in speed and intensity of the reaction will be noticed by experienced eyes).
With this simple test you will be able recognize solid silver from other metals as nickel silver, white metal and so on.

As mentioned above, however, the outer surface of a silverplate object is silver in all its aspects, including the chemical composition.
Therefore, depositing the liquid on the outer surface of an item, the reaction will be anyway red, whether it is or is not solid silver.

What to do to obtain a decisive result?
It is necessary to remove a thin layer of metal on a hidden part of the object, as under the base or in an other area that does not compromise the aesthetic of the piece (consider that silver plate has a subtle layer of silver, thus the part to remove can be minimal).
After this operation, and having thoroughly cleaned the uncovered part, place a drop of reagent on the surface. The red color will confirm that it is solid silver, no reaction or a greenish color will reveal that it is silverplate.
In case of doubt, repeat the test after a thorough cleaning. The procedure is slightly invasive (a small layer of metal will be removed), but working in the right place the object will not suffer perceptible damage. Moreover, on solid silver pieces, an accurate sanding and polishing will remove any trace of the test (but this is not possible in silverplate items).

For cutlery (or other pieces with no "hidden" parts) the test with chemical reagent is not possible without damaging the object.
In this case, you can make a proof with a "stone of comparison" (can be purchased in the same stores that provide the reagent).
Two scrapes on the same surface of the metal will be necessary. The first strip can be misleading, because it may contain parts of the silvered surface; the second should contain only the underlying metal.
Place a drop of reagent on the strip and, with the procedure previously described, the presence or absence of the red reaction will confirm the quality of the metal. This procedure is apparently less invasive. Nevertheless, it leaves a little smear on the metal surface.

Now, some useful suggestions for people interested to the matter.

Do not forget that the reagent is a chemical product, corrosive and toxic. It is necessary to keep the product out of reach of children, to handle it with care and to avoid skin contact and ingestion.
To obtain reliable results on the chemical reaction, the test requires an absolutely clean surface and the use of the reagent "as sold", without any addition, dilution or contamination.

This product is readily available for a few dollars in the stores dealing with materials for gold and silvesmiths and on the Internet (search for liquid silver test, testing silver, reactif argent, silver testing solution, etc.). A great variety of packages is available. Some companies (in the USA) use a package similar to the eye drops bottle (by far the most convenient, allowing to pour the drop directly on the piece). Other companies sell the reagent in a phial of thin glass (once broken, is necessary to transfer the liquid to a suitable container). Another option (found in Italy) uses a bottle with a plastic spoon to pick up the liquid. It is absolutely necessary to pick up the liquid with a tool made a material that does not react with acids, such as glass or plastic, never metal. It is also required a thorough cleaning of the spoon after its use, to avoid the introduction of contaminants into the liquid.

Following these suggestions you should be able to test your objects and ascertain if they are or are not made of solid silver.
The situation is different if the object is not yours, and you wish to submit to test an object you intend to buy.

In my opinion, the test is not necessary if you are negotiating with a professional dealer who issues written guarantee of the quality of the metal.
More caution is needed if you are dealing with a non professional seller on a flea market or a garage sale. In this case, arranged the price and before paying it, you can request to test the piece presented as solid silver.
In my experience, is rare that the seller objects to your request if you declare that, in case of refusal, you give up the purchase.

Great care is necessary in the transport of the reagent, as a minimum leakage may cause personal injury or ruin your clothes.
Usually, I pour the product in an empty eye drops container, thoroughly washed and dried.
To prevent drops oozing (due to temperature and / or pressure variation) is necessary to seal the bottle in another envelope such as a plastic bag.


NOTE: In this writing I describe the use of the potassium dichromate, which is probably the most used reagent in Europe.
Elsewhere, for example in the East and in the United States, a common alternative is pure nitric acid, of which I have no direct experience. This acid gives reactions of different colors: a creamy color for sterling silver or other higher fineness, grey for 800 silver and light green in various shades as the title goes down. The advantage of this system is the approximate indication of the alloy title.
It would be interesting to obtain information about this test by someone well acquainted with the matter.