Tension set rings are unique because the ring acts as a spring to hold the stone, exerting about 12,000 pounds per square inch of pressure to hold the diamond or sapphire in place.  As a result, tension sets tend to be wider and thicker than conventional prong settings in order to perform this magic of physics.   These settings are not for every one.  Clients tend to be either engineers (who appreciate the math involved), spouses of engineers (who appreciate engineers) or people who like modern minimalist design.  No matter why you like them, these rings are unique and only available from the most skilled of jewellers.