Thank you for sending over those photos.
Based on the marking I can read, the earring is a modern piece, made in Italy circa 1980's-1990's.
The earring has what appears to be a large pink semi-precious Topaz set in a sterling silver backing. In the current market pairs of these earrings usually bring between 25-40USD in retail settings.
The upside down marking has been cut off but appears to be numbers, which quite possibly would be a pattern or size number inset by the maker.
We see lots of this modern Italian jewelry which was purchased on QVC and in department stores that lacks a true maker's marking. Many times it was on the original label or sticker or sometimes not at all.
I hope this information was helpful to you today.
Best of luck with your earring .
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