A Hallmark is a stamp engraved somewhere on a piece of Jewelry, it will give you the metal type, i.e 925 means sterling silver, 10k means that the gold content is 10 parts out 24 or. 41.7% gold, 14k is 58.5% gold or 14 parts out of 24. Some Jewelry may also have a maker's mark hallmarked (stamped) along side the metal information. There are other marks like HGE or GE, which tells you the item is plated. the letters GF mean that it is gold filled.
I sure try to be the high bidder, it's a gorgeous Ring Miss Evelyn, You know how much I love Your auctions, wish I could be a Mini Mouse in Your Jewelry Box, I would have a blast, lol have a good night and sleep well