Very old silver ring

After consulting with knowledgeable historians - jewelers - the conclusion is as follows: The crown part of the ring (front part) is significantly older, at least 100+ years, but the band is much newer, thus a beautiful ancient wonder is brought to life with the possibilities of the 70s. There are multiple hallmarks on the band. The stone of the ring is not glass, as testing with a tester shows 5 out of 6 on the Mohs scale. The hallmark office has a one-month queue - hence I am selling it as it is. Beautiful, ancient, and mystical, it leaves my collection. Size 17.5 and 7.8 weight.