Corvidae Antique has dated this piece to the Georgian era.
More photos to follow, or see here: https://corvidaeantique.com/products/antique-georgian-emerald-high-carat-gold-ring

SIZE: M and a half (UK), 6 and a quarter (US).
WEIGHT: 1.5g.
MATERIALS: 18-carat gold, emerald.
HALLMARKS/STAMPS: None. The ring tests as 18-carat gold.
ERA: Georgian (c.1714-1837).
CONDITION: One of the little gold balls along the edge is missing, as are some of the claws. All the stones are firmly set, though one has sunk a little and one has a chip, see photos.
Diamonds and paste (crystal) were usually foil-backed up till the mid-19th century to make them reflect the candlelight better. Brilliant cut gemstones didn't appear until later and the old cuts didn't sparkle as much as modern stones so it gave them a little help. Practically, it just means you should keep them away from water to avoid it leaking behind the stones and damaging the foil - don't wear them to go swimming or do the washing-up!
Corvidae Antique has dated this piece to the Georgian era.
Hand picked jewellery from a friendly family business
You can view the stock and full dealer information on the Corvidae Antique Profile Page