Silver is 99.9% pure elemental silver.
Sterling Silver is 92.5% silver and 7.5% other metals, usually copper.
The stamp .925 indicates that at item is 925 parts silver out of 1000 parts, the remaining 75 parts are usually copper but can be other metals.
Read more about silver here Not All Silver is Created Equal
What is Coin Silver?
Coin Silver, when used in association with vintage Native American jewelry, is a term used to refer to the alloy that resulted when pre-1965 US silver coins were melted down to reuse in jewelry making. Coin silver made from US coins has less silver than sterling silver (90% compared to 92.5% in sterling silver) but that doesn’t necessarily make coin silver jewelry less desirable. In fact, because coin silver jewelry is usually older and hand hammered, it might be more valuable than if it were made of sterling silver.
Vintage Mexican coins often had a silver content above that of US coins, therefore was softer and easier to hand hammer and preferred by some old-time silversmiths. Some Mexican coin silver jewelry will test as high as sterling silver.
Early Native American craftsmen made jewelry directly from the coins, heating the coins in a fire pit or forge and hammering them into shape. Items like this often have some faint residual impressions from the coin design remaining.
They also made ingots by melting coins and pouring the liquid metal into molds to form ingots (blocks or bars). They then would hand forge, or hammer, an ingot into the shape of a bracelet or other item. It should be noted that some vintage ingots are “blends”, that is mostly Mexican coins with a few US coins thrown in OR mostly sterling silver with a few US coins thrown in or any variation thereof. That’s why the exact silver content will vary widely in the vintage jewelry.
This 1930’s bracelet was hand forged and tests at least as high as sterling silver, so is one of those “blends”.