F & S would be the sponsor mark - F. Fattorini & Sons (Fine Retailers & Jewelers, London, UK) - ca 1897 - 1952
the "turban" followed by the double digits 22 would be the hallmark gold crown 22. This is a UK gold standard mark - on 22ct GOLD - ca 1844 - 1974.
22 carat gold is 916 parts per 1000 or 91.6% gold. It is high quality gold, and is very yellow and because it is very soft also hence the reason, why the antique gold ring is out of shape in places. A reputable jeweler can fix this.
One of the remaining letters is a date letter, not sure which one without a photo.
