Marks on Jewelry: Deciphering Value

When we discuss metals, specifically in reference to jewelry, we need to know some basics about the metals used in jewelry making. There are two main categories we can look at; Precious Metals and Base Metals. Precious Metals include; Gold, Silver, Platinum and Palladium. We will not discuss Palladium much as we do not commonly come across jewelry made with this precious metal. Base Metals include; Copper, Brass, Pewter, Stainless Steel and Titanium. Most of the metals listed, both Precious and Base, are alloy metals.

“Alloys are mixtures of various elements. Alloys can be a “base” metal, like brass, or a “precious” (more costly) metal, like sterling silver or karat gold. Jewelers and engineers create alloys to change the color, melting temperature, and/or strength of elements. For example, solid gold is too soft for most applications. To make it stronger, it is alloyed (mixed) with other elements. Base metal is a term in the jewelry industry for metals used in costume jewelry. Base metal is any metal that is not one of the noble or precious metals. Base metals may be plated or raw. In costume jewelry, base metals are often plated with a very thin layer of gold, silver, nickel, rhodium or other metal on the surface of the bead, finding, chain or other components.”

The most precious and desirable of metals is Gold. Gold has enticed man for millennia. “Gold is a very soft metal making it one of the best metals for jewelry making. In its purest form, gold can be too soft to use and is often mixed with metals like zinc or copper. Gold is measured in weight with 24 Karat being the purest form of gold (99.9%) right down to 10 Karat (41.7% pure gold). Some costume jewelry is made with gold plate, which is a base metal covered with a very thin layer of gold.”

The markings we find on jewelry are our key to determining the value of a piece. There are various marks one can find on gold jewelry including assay marks, maker or manufacturer’s marks and purity marks. These marks can vary depending on their country of origin or their intended market. For example, a gold ring made in England typically will have 2 to 4 marks to include a purity mark, an assay office mark, a date mark and a maker’s mark. On the other hand, a ring produced in the USA will typically only have a purity mark and possibly a Maker’s mark or a mark indicating gemstone types such as CZ (Cubic Zirconia) or SOL (Solitaire Diamond).

18K or 14K: These tell you how many gold parts there are in relation to the other metals mixed in. For example, an etching or stamp that says “18K” means the jewelry is made up of 18 parts gold and 6 parts of another metal.
750 or 585: These marks are more common outside the United States, and tell you how much gold is present out of 1000 particles. 24 karats of gold would be equivalent to 1000. A stamp of 585 means that 585 parts out of 1000 (or 58.5%, the same as 14K) are gold. Other common marks on jewelry include:

GP: This stands for “gold plated” and means that the jewelry has a thin layer of gold on top of another metal (usually copper, silver or brass). Sometimes the mark “GP” will be accompanied by the karat weight of the plating, such as “18KGP”. The percentage of gold in a gold-plated piece is usually 0.05% or less. Eventually, the gold will tarnish or rub off.
GF: This indicates the jewelry is “gold-filled,” meaning there is a thin layer of gold bonded inside a different base metal.
HE or HGE: If you see this marking, it means the gold in your jewelry has been layered on using a high-grade electroplating process. Just as with GP and GF, these designations tell you the piece doesn’t actually contain gold.
RGP: RGP means rolled gold plated jewelry. The term that is used in jewelry making called rolled gold plated (also known as gold overlay) uses a bonding process but it does not use as much gold as gold filled pieces of jewelry. In fact, rolled gold plated pieces must have at least 1/40th amount of gold to the total weight of the piece. When a piece of rolled gold plated jewelry is marked, it may indicate the fraction of gold used in the rolled gold plating process such as 1/40 14KGP.
GF Gold Filled
P Plumb Gold (this shows the item is at least the amount of karats shown on the stamp)
KP Karat Plumb (this means the item is at least the karat listed but maybe more pure)
Pd Palladium
PT Platinum
PLAT Platinum
Silver Sterling Silver
SS Stainless Steel
St Steel Stainless Steel
cw Carat Weight (typically will be an indicator of the gem or diamond weight)
CZ Cubic Zirconia
SOL Solitaire Diamond
4, 5, 6, 7, etc… If a low number, it is typically an indicator of the ring size.
Like Gold, Silver marks can vary depending on when and where they are produced.
American silver jewelry marks are fairly simple, usually including a purity mark, and sometimes a maker’s mark. Because Sterling Silver is 92.5% silver, the common purity mark used today is “925.” Most vintage Sterling Silver pieces have the older marks: “STERLING,” “STER,” or “STG.” Some modern jewelry today will use “STERLING” either with “925” or without it, usually in conjunction with the maker’s mark. British silver jewelry marks are the most complex, as they include various letters and symbols. British hallmarks have been used for over 500 years and have changed over time. Hallmarks include a Standard or Purity Mark, a City or Town Mark, a Date Letter, a Duty Mark, and a Maker’s Mark. Not all pieces will have all of these marks.
Common Silver Marks: 800, 850, 900, 925, 950 and 999.

Platinum jewelry will be marked with the following
PT or PLAT followed by:
850 – 85% Platinum
900 – 90% Platinum
950 – 95% platinum
999 – Pure (very little metals added) Platinum

Once you have determined what type of metal your jewelry piece is made from, you can then more easily determine the value of your piece. There are many applications you can download to give you real-time market value for precious metals. One application I have found useful and was recommended is the ScrapIt application by KITCO. You can download this application from your GooglePlay app store or the Apple Store. This application gives you current market values for Gold, Silver and Platinum and will allow you to approximate a value.