Sterling silver is an alloy of silver containing 92.5% by mass of silver and 7.5% by mass of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
Argentium silver is a modern sterling silver alloy which modifies the traditional alloy (92.5% silver + 7.5% copper) by replacing some of the copper with the metalloid germanium. As it contains at least 92.5% silver content of the traditional alloy, it is still referred to as sterling silver.
Gold filled, goldfilled, or gold-filled, abbreviated G.F., is lower in gold content than 10 KT (usually 1/20 or 1/12 KT), but much higher in gold content than gold plated, gold washed or gold vermeil. In gold filled a sheet of gold is mechanically applied to the surface of a stronger metal.
Gold filled jewelry has many advantages. It is stronger than karat gold jewelry because the inner core of base metal adds structural strength. It is extremely durable because the gold plating is so thick. Unlike rolled gold or gold electroplate, it is rare to see gold filled jewelry which has lost its gold surface. The luster of gold filled jewelry is generally excellent because the perfectly even thick karat gold sheet produces the rich appearance of fine jewelry.
Other than the monetary value that gold holds, it has some characteristics that is extremely desirable in the jewelry industry. One of the advantages of gold jewelry is it's resistant to tarnish. Gold jewelry keeps its brilliant shine as it does not oxidize.
The Karats used in describing gold jewelry should not be confused with the Carat used in describing diamonds. The Karats used for gold jewelry is a measure of the percentage of gold in the mixture.
Pure gold is too soft a metal to actually be practical for jewelry. It would be easy to bend out of shape and deform. As a result, gold must be alloyed or mixed with other harder metals to be practical for jewelry. This is where the Karat numbers come into play:
- 24 kt (short for Karat) is pure gold
- 22 kt is 91.6% gold and 8.4% other metals.
- 18 kt is 75% gold and 25% other metals.
- 14 kt is 58.3% gold and 41.7% other metals.
- 10 kt is 41.7% gold and 58.3% other metals.