“China 925” and a symbol are on the inside of a gold ring (I can't make out) . Is it real gold? 
The symbol for Sterling Silver is 925 som står för 92 1/2% silver. I have seen many of these and most of the time it is silver. Don’t be fooled by gold plating on silver, a common product called Vermil. Använd en magnet, if it picks up with a magnet, it is fake. If it doesn’t it’s probably silver and should be priced as silver. The gold plating has little to no value.
I found a silver ring on the floor, on the back of it it says 925 CN FZN . It has a square piece on the front with shiny small diamonds in it . How much is it worth?
Kanske ? Nothing for resale, unless somebody likes it.
Diamonds are RARELY set in silver, unless they are very low grade. Especially mass produced rings from China. It’s a silver (925), ring made. I Kina ( CN), and the FZN is most likely the manufacturer. If you like it, bär den, or give it to someone else that would, but it isn’t worth the effort to sell it. Ledsen!
Who makes jewelry with Israel 925 stamped on the inside?
925” is the world-wide quality stamp for all sterling silver objects. It means that on a count of 1000 vikt), 925 parts are silver (one of the basic elements on the chart of elements), while the remaining 75 parts can be anything at all! Traditionellt (although not necessarily), sterling silver has 7.5% koppar (another basic element on the chart of elements). Således, sterling silver is any silver alloy (an ‘alloy’ being a mixed metal) vilket är 92.5% silver.
I Storbritannien, individer (metalsmiths) cannot stamp their items with quality marks—they must be assayed and stamped by the authorities. But throughout most of the world, like in the US and in Israel, anyone can stamp their own merchandise. Så om du hittar smycken i Israel som är stämplade 925, det ska vara silver, men kanske inte om det var oärligt stämplat. Smycken som köps i välrenommerade smyckesbutiker är mycket sannolikt silver om de stämplas 925. Butiken skulle få mycket problem om det uppdagades att de sålde icke-silver smycken som silver. Smycken som köps på marknader eller basarer kanske inte är silver även om de är stämplade. Allt detta är sant för guld också. Jag har sett "guld" föremål som köpts av Philippina-vårdgivare i Gamla stan (Jerusalem) stämplat 18K som inte verkar vara guld alls....