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Silver Plating

Please be aware that the silver calculator is for solid silver jewelry. Solid silver jewelry contains a uniform mixture of silver and other metals throughout the entire piece of jewelry. For instance, a 10g piece of stirling silver (925) jewelry contains 92.5% silver or 9.25 g of pure silver.

On the other hand, silver plated jewelry contains almost no silver. This is done because it is cheaper to use less expensive ferrous metals or non-ferrous (base) metals as the core and apply a thin layer of silver on the outside.

• Sheffield plate - earliest form of silver plating (introduced in 18th century).
• Silver plated or silver electroplated - uses an electric current and a piece of jewelry, which acts as an electrode, inside a silver solution. The silver forms a coherent metal coating on the electrode.
• Nickel silver or Alpaca silver or Silver tone - alloy that imitates sterling silver made from copper, silver, zinc, and sometime iron. It contains no silver.

To recap, silver plated jewelry contains an almost negligible amount of silver metal. The silver calculator is only applicable to solid silver jewelry, not silver plated jewelry.

Silver Hallmarks

A hallmark is a mark stamped on a piece of jewelry certifying the purity of metal used. There are hallmarking laws that apply to the sale of silver jewelry in some countries (such as the Hallmarking Act 1973 in the UK). However, globally there is no standard that must be followed therefore solid silver jewelry may or may not be hallmarked.

Solid Silver Hallmarks

Solid silver jewelry will have its purity stamped on it. The purity is expressed in the fineness scale which is expressed as parts silver per thousand or, less commonly, as a percentage (%). Please refer to the scrap metal price table for the common silver type names and the relationship between percentage and fineness. Sterling silver is by far the most common silver alloy, and may be hallmarked "STERLING", "STER", "STR", or "925".

Please be aware that silver jewelry may be hallmarked a certain percentage or fineness and may not have that level of silver content or may not be solid silver jewelry at all. Hence silver jewelry needs to be tested when valuing its silver metal content.

Silver Plated Silver Hallmarks

• Silver plated or silver electroplated - "SHEFFIELD", "SP", "S.P", "SEP", "HSP", "S.E.P" or any mention of "PLATE" or "PLATING".
• Silver filled - "SF" or "S.F".

You may choose to scratch a suspected plated piece deep enough to see the underlying metal to confirm the jewelry is not solid silver. As this is a destructive test, choose a discreet spot which will not be visible when worn, for example, around the clasp on a silver chain.

Silver Testing

As a silver buyer this is important to remember silver metal is expensive relative to most other metals therefore there is always an economic incentive to pass lower content silver as higher content silver. Hence, remember to test for silver purity.

Magnet Test

Silver is only weakly magnetic. If in the presence of a magnet it sticks strongly, then it is likely to have a iron (ferromagnetic) core. Only use this test in conjunction with other tests as the item may have a core which is not made of iron.

There is variant of this test for bullion bars, called the sliding test, where you use a strong magnet and slide it down a bar at forty-five (45) degree angle. As silver is weakly magnetic, it should cause a "braking effect", so it should slide slowly relative to an equivalent non-magnetic item.

Ice Test

Silver has a very high thermal conductivity. When a piece of ice is placed on silver bullion it should begin to melt immediately as the temperature of the bullion is transferring to the ice very quickly. This test is mainly only practical for silver bullion not silver jewelry.

Ring Test

Silver coins when tapped should make a distinguishable bell-like sound.

Touchstone testing

This test involves the use of strong acids so before you begin this test, please ensure you have the personal protective equipment (PPE).

• Safety goggles - to protect your eyes
• Protective gloves - to protect your hands
• Water, baking soda, paper towels - to dilute, neutralize, and clean acid spills respectively.

Also ensure you are in a well-ventilated area as the acids are strong and noxious.

This test involves rubbing the jewelry on a touchstone, an abrasive stone similar to fine sand paper, leaving behind some metal from the jewelry. The silver testing kit will have one or more bottles of acid. There will be instructions with each specific test to indicate what color change to expect for what purity of silver. Note the scale of the test is applicable for (the minimum % silver the test works for) and also note that the acid in the test typically has a relatively short shelf-life.

X-Ray Fluorescence

This method of testing is non-destructive and is suitable for normal assaying requirements. A computer, called a x-ray fluorescent (XRF) analyzer, will use x-rays to determine the composition the the jewelry. It takes less than a few minutes to complete and the results may be printed out. Popular brands include Thermo Scientific Niton range or Olympus GoldXpert or DELTA Precious Metals XRF analyzers.

There is also a method called x-ray fluorescence assay which involves melting a sample into a uniform composition before testing the sample on a XRF analyzer. This method is more accurate then a XRF analyzer but less accurate then a fire assay.

Fire Assay

This method of testing is totally destructive however provides the greatest accuracy. The first part of the process is called fusion which involves mixing the sample with a fluxing agent (which helps melt, fuse, and separate the precious metal) and heating it to a high temperature. The second part of the process is called cupellation which involves using a collector, such a nickel or lead, to extract the precious metals.

The precious metals extracted from fire assay is then analyzed by one of the following methods:

• Flame Atomic Absorption (AA)
• Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES)
• Inductively Coupled Plasma-Mass Spectrometry (ICP-AES)
• Instrumental Neutron Activation Analysis (INAA)

Miscellaneous Equipment

Other equipment that is common in silver testing kits include:

• Jewelers loupe provides magnification to see small details more closely. Handy for inspecting hallmarks.
• Digital scale for precisely measuring the weight of jewelry.
• Diamond tester for confirming a precious stone is a genuine diamond (or moissanite).