This time I would like to inform you on my diamond blog about my favorite diamond jewelry - tension diamond ring. A tension ring is a type of finger ring in which the gemstone is held in place by pressure rather than prongs, a bezel or other mounting. The metal setting is actually spring-loaded to exert pressure onto the gemstone, and tiny etchings/grooves are added to the metal in order to create a shelf for the gemstone's edges to rest. The gemstone appears to be suspended in the air with nothing holding it in place.

The first tension ring was created in 1981 by the German company Niessing, but the general concept of tension settings has been around for over 40 years as it was developed in the late 1960s by a Niessing employee named Friedrich Becker[7]. The original tension ring designs were very bulky in order to provide the strength to maintain sufficient pressure on the suspended stone. These early rings are so bulky that they resemble a solid metal inner tube wrapped around the finger. Steven Kretchmer was the first American adoptee of this design, and perfected the work hardening process that allowed his ring designs to be less heavy than the Niessing originals without sacrificing strength. Other ring designers followed Kretchmer's adaptations within a few years.

A major difference between tension settings and other settings is that tension settings are only manufactured after they are sold while other settings are often manufactured first and then sold to consumers. There are several reasons for this difference. First, tension settings can not be resized easily as resizing them will remove the spring-loading effect. Instead of resizing a tension setting, the manufacturer actually has to melt down the old setting and create a new spring-loaded tension setting that is appropriately sized. Second, tension settings are calibrated to the exact specifications of the stone that they will hold, therefore they can not be manufactured until the customer has selected the gem that will go inside. Unlike other settings which can be manufactured ahead of time regardless of the stone that will ultimately be placed inside, each tension setting is designed specifically for the stone it will hold. The tension setting is calibrated by a computer using light to identify the exact places where pressure must be applied on the gemstone in order to avoid fracturing it through even pressure distribution.

Because tension settings place such pressure on the stone, only three types of gemstone can be placed in a tension setting: diamonds, rubies, and sapphires. Additionally, tension setting manufacturers must be careful which stones they place in tension settings; a stone that either has significant inclusions or is too soft will fracture under the intense pressure of the setting. The Mohs scale is a reliable way to rank a gem's hardness; generally gems that have a Mohs hardness of less than 9.0 cannot be placed in the setting.

It should also be noted that the term "tension setting" is, from the perspective of physical science, a misnomer. The stone is not held in tension (a pulling force) but in fact in compression (a pressing force.) The ring however is placed in tension by the presence of the stone. Although tension rings are unique in design and make a wonderful engagement ring, they can also have matching wedding bands made for them.