“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 che sta per 92 1/2% argento. 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. Usa un magnete, 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?
Forse ? 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. In Cina ( CN), and the FZN is most likely the manufacturer. If you like it, indossalo, or give it to someone else that would, but it isn’t worth the effort to sell it. Scusa!
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 in peso), 925 parts are silver (one of the basic elements on the chart of elements), mentre il restante 75 parts can be anything at all! Tradizionalmente (although not necessarily), sterling silver has 7.5% rame (another basic element on the chart of elements). Così, sterling silver is any silver alloy (an ‘alloy’ being a mixed metal) che è 92.5% argento.
Nel Regno Unito, individui (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. Quindi, se trovi gioielli in Israele che sono timbrati 925, dovrebbe essere argento, ma potrebbe non esserlo se fosse stato timbrato in modo disonesto. È molto probabile che i gioielli acquistati in gioiellerie affidabili siano d'argento se stampati 925. Il negozio si troverebbe in molti guai se si scoprisse che vendono gioielli non in argento come argento. I gioielli acquistati nei mercati o nei bazar potrebbero non essere d'argento anche se recano tale timbro. Tutto questo vale anche per l’oro. Ho visto oggetti "d'oro" acquistati dagli operatori sanitari filippini nella Città Vecchia (Gerusalemme) timbrato 18K che non mi sembra affatto oro…..