I have a ring it has a diamond cluster, I believe it is set in platinum, the band is yellow gold tho. It has exactly the same markings as yours. I have been searching for over a year and you are the closest I have come to find a maker.
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Same marking with Stuller by: Kelly
I have a ring with same marking and it also has Stuller on it.
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I have the same mark on my engagement ring by: Anonymous
I have the exact same mark on my engagement ring which my fiance bought second hand. I have been searching for more information!
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Starr Jewelers | Asterisk Marking by: Anonymous
Starr Jewelers in Kalamazoo, MI used that mark around that time. I'd definitely check it out as a possibility.