Gem-set rings for men
Although, like most jewelry, gem-set rings are more usually worn by women you can find examples which were created with men in mind. Of course a man, if he was so inclined, could wear any ring he wanted but by and large men stay away from rings in general and gem-set examples in particular.
Stone-set signet rings seem to be the one type that some males are willing to make an exception and get something with a gem. These rings are distinctive and certainly are not the same thing as is worm by women. The front of the ring is usually a bit thicker than the rest and is pierced to take a stone. Not something that you would want to buy as a gift for a man but something a man might like to pick for himself.
If you are looking for such a thing then you would do well to make your purchase in a real world jewelry shop, rather than Online. Most men are unsure about making a jewelry purchase and seeing something in the flesh before you hand over the money will help to ensure that you make the right decision.