It is illegal for any plated or fake silver item to be stamped or hallmarked with “sterling" or 925.
925 silver oxidizes when exposed to air leading to chemical changes in its wake. Using a soft white cloth, rub a small part of the jewelry, if the surface produces a black mark it would mean that the product is sterling silver. On the other hand, the color change would be absent in fake merchandise.
Markings
There are markings such as “S925”, “. 925”, and “925”. This gives assurance that the silver is indeed a 925 sterling silver. However, there are some sterling silver that don't have these marks so don't directly assume that the silver is fake if it doesn't have the mentioned markings.
Sterling silver, in general, is the real deal. It may be a different type of silver, but that doesn't change it's authenticity in the jewelry industry. However, there are those who try and pass off fake sterling silver as the real thing. There are many ways that you can tell sterling silver from fake materials.
Some pieces of gold jewelry feature a hallmark reading “925 Italy.” This doesn't mean anything particularly important for most jewelry buyers. “925 Italy” gold jewelry hallmarks simply indicate that a piece was made in Italy. Technically, though, it still consists of a sterling silver base with gold on top of it.
Look for a Hallmark Stamp: Look for a stamp or mark on the piece that says "STER," "925," "800," OR "999." 925 or STER means it's 92.5% pure silver, which is traditional sterling, 999 means 99.9% pure which is fine silver, and 800 means it's 80% pure silver or a lower quality than sterling silver.
The Magnet Test
"If your magnet sticks strongly to the piece, it has a ferromagnetic core and is not silver." Fake silver or silver-plated items are generally made of other metals. This is an easy test that can give you a good idea on whether your item is real silver or not.
As we mentioned, true sterling silver jewelry has a silver stamp that identifies the percentage of pure silver that's found in the piece (925, SS, 92.5, etc.). Silver-plated jewelry won't have this silver stamp.
Since sterling silver has a lower percentage of silver than pure silver, sterling silver is less expensive. Of the three types of metals, it's typically the least expensive choice. You'll also find more jewelry options in sterling silver since it's a more accessible material to mold into different shapes.
If you have a gold piece with a 925 mark, it's most likely sterling silver underneath gold plating. You'll normally see this kind of stamp on a gold vermeil (pronounced as "ver-may"), meaning that it's sterling silver that has gold plating.
Well, it turns out “925 China” is a standard marking on jewelry to denote sterling silver jewelry. If you see “925” or “925 China” stamped on what you thought was your gold jewelry, then the jewelry has 92.5% sterling silver content and is merely gold-plated. The remaining 7.2% is composed of other metal elements.
925 - U.K. [Sterling], U.S. [Sterling - since c. 1870], Ireland [Sterling], Denmark [since1893], Netherlands [current], Israel.
Sterling silver jewellery differs from silver plated in what it is made of. Sterling silver is an alloy, made of 92.5% pure silver, and 7.5% other alloy. These other alloys tend to be copper or zinc. Due to the pure silver constitution, sterling silver is often known as 925 silver.
You might not leave a mark on fake jewelry. However, gold-plated lead is even softer than gold, so an extremely deep mark may also indicate a fake. Rather than damage the jewelry yourself, you may want to simply look for marks made previously.
The stamp will typically be on the clasps of jewelry. Some counterfeit gold will have a karat stamp on it, but rarely have a manufacturer's name.
Your 925 silver is valuable and is certainly worth selling if this is something you wish to do. Though knowing how much your silver is worth can be difficult to determine without an appraisal. How much silver you are selling and the current value of silver can influence what your item can be sold for.
Jewelry considered "fine silver" must contain at least 92.5% pure silver. The remaining 7.5% is typically made up of copper and nickel. A piece of genuine sterling silver will have the words "sterling" or "925" stamped or otherwise marked on it.
925 Silver. Sterling is the jewelry quality standard in the United States and most world markets. It is an alloy of 92.5% silver. The remaining 7.5% is usually copper though it is sometimes other metals such as nickel.
In 1999, a new format of English hallmarking on objects of Sterling Silver was initiated consisting of a maker's mark, the assay office insignia and a 925 symbol.
When a ring, chain, pendant, earring, or other piece has 925 stamped on it, almost like a tiny engraving, it means that it is 92.5% silver and 7.5% of another metal. This 925 is called a “hallmark” and indicates high-quality sterling silver. Other hallmarks of superior sterling silver are “STG", "S.S.", or "STER".
Tarnish is the oxidization that occurs when air-borne sulfurs and chlorides are present, causing a yellowish cast on the sterling silver. If left without being cleaned, the tarnish becomes brown and eventually turns a dark and iridescent purple/black.
Ice Cube Test
All you have to do is place an ice cube on top of the piece of silver and see how fast it melts. The ice melts rapidly, even at room temperature, if the silver is real. Thermal conductivity easily passes heat through. However, if the silver is fake, the ice will melt slowly.