Identifying an Antique 'Ed' Diamond Hallmark Ring - Expert Analysis

Question
Hello and thanks for your help!
I have a ring that I purchased at an antique jewelry shop in New Orleans and was told it was an antique, but I'm not sure. It is marked 750 (which I am assuming is 18K) on the inside and has a hallmark that is the silhouette of a diamond with the letters "Ed" on the inside. I'm hoping to figure out at least who made the ring so I can work further to determine whether the ring is antique, vintage, etc.
Thanks again!

Answer
Hello Shay and thank you for your inquiry. Your ring is probably as marked 18K and the mark is likely the manufacturer.  However, I have been unable to locate the mark for more information. To verify the 750 mark is valid it would be wise to have the ring tested by a jeweler or gemologist. Most American jewelry is marked with the K karat mark so your ring may indeed be older. Your jeweler could also give you this information.  If I find the mark you describe, I will get back with you and enjoy your ring !