Can I design a custom ring with a tension setting?
You can, but I need you to understand what you're actually asking for before I say yes. A tension setting holds a diamond by compression alone - the metal...
You can, but I need you to understand what you're actually asking for before I say yes.
A tension setting holds a diamond by compression alone - the metal grips the stone at the girdle, usually from three or four points, with no prongs, no bezel, nothing above the crown. The ring is machined or cast slightly undersized, then the shank is literally sprung open, the stone is seated, and the metal is released to clamp down. When it's done right, the stone looks like it's floating. That's the seduction of it.
I've built maybe forty tension-set rings in twenty-two years. That's not a lot, and there's a reason for it.
What the sales floor won't tell you
Most jewelers who offer tension settings are buying pre-made mounting heads from a casting house - Stuller has a few, and they're fine for what they are - and setting the stone in a controlled jig. That's different from a true tension setting where the shank itself is the clamp. The real thing requires a stone with a very specific girdle thickness and a very specific tolerance for the stress involved. If the stone has a thin girdle - and a lot of older cuts and poorly-cut modern stones do - the clamping force can chip it. I've seen it happen. It happens at three in the morning when you're tired and the stone seats just a little wrong, and suddenly you're looking at a 1.2 carat diamond with a feather you didn't put there.
The other problem is resizing. A tension-set ring cannot be sized in the conventional sense. You can't cut the shank, add metal, and re-solder without destroying the tension mechanism. If the client's finger changes size - and it will, over a lifetime - the ring either gets rebuilt from scratch or the client wears it on a different finger. I tell every client this, and about half of them still want the ring. The other half walk away, and that's fine.
When I'll say yes
I'll build a tension setting under three conditions:
- The stone has a thick, even girdle. At least 2.0 mm, preferably more. If a GIA report shows "girdle thickness: very thin to thin," the answer is no. I don't care how much you love the stone.
- The metal is 18k white gold or platinum. 18k yellow is too soft for a reliable clamp. Platinum alloys - I use 950Pt/Ru - have the right springiness. 14k is possible but I won't guarantee it for daily wear.
- The client signs a resize waiver. I explain it, they understand it, and it's in writing. No surprises five years later when the ring doesn't fit.
Last spring a client named Priya brought in a 1.04 carat old European cut, F/VS2, with a girdle that was a chunky 2.3 mm at its thinnest. It was clearly cut to survive a carriage-wheel, and I knew immediately it could handle a tension mount. We built it in 18k palladium-white, four-point clamp, and it's one of the best tension rings I've made. Priya wears it every day, and so far - knock on wood - no issues. She knows what to watch for.
The honest advice
If what you love is the floating look, ask me about a half-bezel or a cathedral setting with an open gallery. You get a similar visual effect - the stone seems to hover - with none of the mechanical risk. A half-bezel, properly done, will let you resize the ring, re-tip the setting, and replace the stone if you ever need to. A tension setting is a commitment to that stone, in that ring, forever. Most people don't actually want that much commitment from a piece of jewelry.
But if you've read all of this and you still want the tension setting, I'll do it. I'll quote six to ten weeks, about $1,200 to $2,800 for the mounting depending on metal and complexity, and I'll ask you to bring me the stone in person so I can check the girdle with my calipers. If it passes, we move forward. If it doesn't, I'll tell you to your face. That's the job.