The 925 or .925 marking is the most common for silver jewelry, though 900 and .999 are possible. Common markings for gold jewelry include 24k, 18k, 14k and 10k. Other common gold markings include 999 or .999, 750, .585 and .417.
The common markings on fine jewelry denote the percentage of precious metal in the piece. The 925 or .925 marking on silver indicates that the metal is 92.5 percent pure silver. This percentage of pure silver makes it sterling, which is the most common form for making jewelry. The other silver markings also indicate how much pure silver is in the metal.
Markings on gold jewelry are slightly different in that they're based on a 24-karat scale. Jewelry marked 24k contains as close to 100 percent gold as possible. Gold jewelry can also bear the marks 999 or .999 to indicate almost complete purity.
The 18k mark indicates 18 out of 24 karats of gold. Because that is the same as 75 percent gold, some jewelry bears the mark 750. This is the most common purity level for gold. Gold at 14 karats of purity sometimes features the mark .585 for the same reason.
Other gold markings include HGE, GF and GP. The HGE mark indicates the metal is heavy gold electroplate. The GF mark indicates gold filled, and the GP mark indicates gold plate.