In tension setting, a stone is held by the mechanical force of a metal band that was ‘stretched open’ and released back onto the stone, with the stone’s sides lodging into grooves on either side of the band.
This setting technique is very recent (1960’s) because it relies both on modern metallurgy and machinery. The metal of the band is made from a special alloy that gives it the required spring-like quality. The gold, platinum and silver alloys traditionally used in jewellery are not suitable here. The band is streched open using great force with a specialized machine.
In the first attempts for using this technique, the alloys were not perfected enough to retain their ‘spring’ for the many years required in jewellery. This has given tension set jewellery a bad reputation originally. Recently developed stronger alloys are perfectly capable of retaining the necessary tension for as long as is necessary. So the manufacturers argue that tension setting has now become a safe way to set a hard stone. And we see no reason to disagree.
However, there is one thing that should not be ignored. The special way in which tension setting is made, means that they can not be repaired at any general jeweller’s workshop. Like with invisible setting, only the original manufacturer has the equipment and knows the used alloy to be able to perform any maintenance. That means that any necessary work, such as enlarging a ring, is impossible without sending it back to the original manufacturer. They will perform the enlargement by undisclosed processes – probably by making a completely new item to the new specifications.
What the customer should keep in mind is that in traditionally made jewellery, maintenance and repair is straightforward and readily accessible. Century old items can still be modified and maintained to very high standards today. With tension setting, the manufacturer’s word is a customers’s only guarantee.