Tell me about 750 stamp on silver please

If it turns milky and "lifts" you've got silver. I've used 18k acid instead of silver acid for years, since someone else told me. Silver acid goes bad too quickly and it's hard to read. Once you see the silver reaction once it's unmistakeable. Do the same thing with a piece of known sterling and you'll be absolutely sure.

 

CM = cast metal ?

 

The mark looks more like CM750... Isn't 750 a mark indicating a measure of 18k gold?

 

Personally, can't say I recall seeing a numeric '750' silver stamp on anything other than mid to late 19th century German silver - until now. Here are two German .750 fineness spoons, one marked as '12 LOTHIG', the other '750':

https://www.worthpoint.com/worthopedia/pair-of-fiddle-design-serving-stuffing-spoons-19


Since you've already mentioned its being "quite roughly cast", won't comment on the poor quality of the bracelet any further - my first thought was Indian of fairly recent manufacture, and found a site with these '750' silver pieces by three different Rajkot, India manufacturers (there are probably more items, but I found the site awkward to navigate - https://www.jewelxy.com/products/silver-jewelry/manufacturer/silver-kada-39988):









~Cheryl

 

Maybe it's as simple as they are using 750 to denote lower fineness silver, ignoring the fact that it's meant to be a gold standard?. Who knows but it's been an interesting discussion!. Thankyou for all your input.