How to Sort Gold With Electroplating

Some jewelry is made of a less-precious core electroplated with gold.

Electroplating is the coating of one metal with another using electrical current. Some "gold" jewelry may not be made of gold through and through. It may be plated with gold covering a metal of lesser value. Electroplating is known for decorative uses, but it also has industrial applications, even when a precious metal such as gold is involved. A person trying to determine the value of electroplated gold jewelry may wish to sort the better-coated pieces, which are likely both more attractive and valuable, from lesser ones. In industrial settings, the measurements of the metallic coating may be vital to the functioning of a part.

Instructions

1. Sort the gold items by the thickness of the electroplating. The gold coating is measured by microinch, one-millionth of an inch, or micron, one-millionth of a meter. Although most American industries use the English system's microinches, the jewelry industry uses the metric system's microns. Gold electroplate must be 7 microinches, or 0.175 microns, in thickness to be marked as such, per rules established by the Federal Trade Commission. The thicker the coating, the more gold is present in the piece of jewelry.

2. Sort the gold items by the hardness of the electroplated coating. Older electroplating needed to be thicker than 5 microinches to prevent the coating from rubbing or wearing easily. A piece of jewelry that did not maintain its gold coating would lose attractiveness and value as the metal rubbed or flaked away. Newer methods have enabled the use of thinner coats, which may require the FTC to revisit its standards for electroplating to be 7 microinches.

3. Sort the gold according to the percentage of pure gold. This method primarily is used for engineering purposes. The gold is classified by type according to its relationship to a 24 karat gold "theoretical purity" standard, with a minimum of 99 percent needed. It can be further graded and sorted as A, B or C according to its hardness and classified according to its thickness. Specific parts may require specific types, grades and classes of gold electroplating to stand up to the rigors of industrial use.

References

• Caswell: What is Electroplating?
• Artisan Plating: Measuring Layer Thickness on Gold Plated Surfaces