Identifying a Vintage Black Onyx and Diamond Ring: A Jewelry Appraisal Inquiry

Question
Hello there... Last month my great Aunt passed away, she was very special to me and I got one of her rings.  I love it, and really don't care if it is worth anything... but my question is how old is it?

The information that I have is...  it is a square black onyx (it is pretty big) with a small diamond in the middle of the onyx.  The setting is very heavy in 10k yellow gold.  The stamping on the inside is SP-CO 10K... My great Aunt was 95 when she passed and my mom is 62, and as long as my mom can remember my Aunt has had this ring.

Answer
Hello Annette and thank you for your inquiry. My resources list SP as being a logo for General Chain Co. in Providence, R. I. They were active in the 1930's . So far, that 's the only SP I've been able to locate. The design you describe was popular during that period of time. If I find out anything more, I'll be sure to let you know. Enjoy your ring !