Try looking into premier design jewelry hallmarks as they use a crown as a hallmark. Ster. Means the ring band is made of sterling silver.b
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Ster is for "sterling" by: Fox
Hi there, The "STER" is an antique purity mark for "sterling".
The crown would indicate the maker. The picture is too blurry for me to see the details of the crown, which is understandable since I know the challenge of taking hallmark photos all too well...Especially the antique/vintage ones that have normal wear from age/use. The crown is often used in antique jewelry from the UK which is where I would start my search for the maker.
Is the star sapphire gemstone modern? It does not appear to show as much wear/age as the rest of the ring.
Hope this helps! If you can get a clearer pic of the crown, possibly I could be of more help.
