Based on the type of gem or its weight, thousands of pounds of pressure per square inch is exerted on it. Which is why a gemstone should have a rating of 9.0 at the least on Mohs’ Scale of Mineral Hardness for a tension set diamond ring. Diamonds have a rating of 10.0 on the hardness measure, so they are perfect for this type of setting, but even sapphires and rubies can be set in the mounting since they meet minimum criteria for that.
The gems used in the setting should also have higher clarity grades, as too many inclusions inside the gem can lessen its strength and increase the likelihood of cracking while exerting pressure. To be precise, the gem should be having a VS2 clarity grade or above as assigned by GIA to create a tension mount diamond ring. Further, to create such settings for a ring, all gems should have a Good to Excellent clarity grade.