14k with diamonds isn’t unusual because 18k is pretty soft so you need thicker, wider bands. Most dainty female solitaire rings use 14k gold (or platinum) because otherwise the ring would deform and thin easily. Rings are the jewelry that gets the most abuse. Any high quality diamond would have platinum prongs/ settings because gold is not ideal or safe for setting for pricey stones.
Ralph has a pawn store special. The ring is hollowed out to lower the gold weight. There was an issue in the 60’s, 70’s, etc… with a surplus of old mine cut diamonds. Everybody wanted the new brilliant facet cut diamonds because they sparkled so much more. All the old jewelry coming into pawn stores for smelting had the old minecut diamonds and the market didn’t have much use of them. Women wanted the superior brilliant cut diamonds. However pimps and men who loved big belt buckles liked the idea of a gaudy diamond rings. They finally had a use for all those low quality mine cut diamonds piling up..trucker and pimp rings.
Also, Elvis had made gaudy jewelry and sunglasses fashionable among middle aged guys that felt alienated by the young hippies. Most of the low level, degenerate gamblers and wannabe gangster in 1970’s Vegas wore rings like this, along with cheap polyester. It suits Ralph in that regard. Square gold rings with monogrammed initials were very popular too.