It's almost certainly the item's "fineness". For most jewelry the gold's purity is measured in units of 1000, often but not always represented as a decimal, with 1.000 being pure gold. Thus 800 (or 0.800 or .800) would mean gold that's 80% pure, with the remaining 20% being other metals added to increase the alloy's hardness.
Not
the stamp shows that the ring is of 14 karat gold piece; to check if it is real or not.
What does it mean
GOLD SHELL = Equals fake or gold plate If the GS stamp is inside of a diamond shape it's the makers mark for Gottlieb & Sons.
14 carat gold
62.5 % gold
Gold electroplate. Not gold.
gold
The stamp "RSC" inside a gold ring typically refers to the manufacturer or jeweler who made the ring, rather than indicating the metal composition. You would need to look for a separate stamp indicating the gold purity, such as "10K" for 10 carat gold. If the ring is a Roman silver coinage, it would likely have a different stamp or markings to denote its origin or historical significance.
The Stamp YAG Means Gold Coated Silver
Palladium
silver