Good Morning Katie! Thank you for writing in and a special thanks for uploading images. It really helps. Blue stones can be difficult to identify even for a gemologist!
However, one simple clue in blue stone diagnosis, and in considering, its age, will be surface wear on the surface of the stone. Under loupe, can you see any signs of scratches, abrasions, rounding of the facet edges? AQUAMARINE is "softer" than TOPAZ or Blue Spinel, (natural and synthetic spinel) on the Mohs scale of hardness, and so the facet edges of the stone, if it is an Aquamarine might look a little worn. Topaz on the other hand, will have sharper facet edges.
Another idea, for a more diagnostic identification, is to take the ring to a local gem school in your area. They often will test, for free, or for a donation, and will let you know if it's worth getting appraised. If it is an aquamarine, or NATURAL SPINEL despite the makers mark, it will be worth getting an appraisal. The color of the stone looks amazing!
I' ll have a little research into the initial mark, however Katie, if this is the only mark on the ring, there's no hallmark for gold purity, it indicates, it's handmade and the maker may not have registered the mark. Thanks for sharing!
