overstock.com, not the best source for jewelers by
far, says that "Invisible settings are a modern solution for a
sleek ring design. Invisible settings are similar to prong
settings, but they hold the stone with prongs under the stone,
rather than around it. This method creates a ring that is sleek and
minimalistic while still having a traditional look.
Overstock is wrong. There are no prongs. The stones themselves have
grooves, a bit like tongue in groove flooring boards, cut just below
the girdle on the pavilion, usually two opposing sides, not all the
way around, though that too is done sometimes.
The invisible part of the mounting is a simple rim of metal almost
like a bezel before you cut a seat and drop the stone into it. A
narrow cut with a graver is made, splitting the top edge of that rim
so now the cross section would be like the letter Y, except not so
wide. (this assumes several stones side by side, and this rail will
hold two of them). when the stone is simply pressed down onto this
split edge, the edges deform and bend inwards, into the groove,
which then holds the stone. Single stones also grooved, can be held
much like bezels, except instead of burnishing the metal over the
girdle, you’re working it into the grooves below the girdle. It ends
up looking as though the stone was just sitting on the metal, not
held in by anything, thus the name, invisible setting. In the case of
multiple stones, often square stones looking a bit like a
checkerboard pattern, the stones are almost touching girdle to
girdle, with no metal extending up above the girdles. What’s holding
them in are those narrow flanges which have bent inwards into the
grooves in the stones. No prongs. And this type of setting work is
difficult enough to do, that precise fitting is critical. I doubt
you’d want to use the CAD to pre cut those flange edges. The graver
does it cleaner.
For your customer, I’d simply suggest that you try to keep the sizes
of whatever prongs you make, fairly minimal. Some CAD designs can
tend to sometimes make such parts a bit clunky and heavy, so this is
what you want to avoid. Tapering the setting so the lower sections of
prongs lean in under the stone, rather than being vertical, also
reduce their visibility and heavy look. But no matter how you do it,
prongs simply cannot be invisible. If you make them too light, they
simply won’t hold the stones securely enough.
If they don’t want to see visible prongs, perhaps you could suggest,
instead a very delicate bezel. Because bezels go evenly all the way
around the stone, You don’t see obvious “clamps” extending over the
stone, and breaking the outline. The bezel does come slightly over
the girdle, but to the same degree all the way around, so it may not
be obvious. They’re also not so prone to being snagged and pulled
back if thin and delicate, and for a bezel to let go, you have to
have some serious damage or have much of the metal worn off the top.
If the width of the bezel (looking down from the top) is narrow, and
only extends a little bit over the girdle, you can have a secure
setting with metal that remains delicate and minimal looking, yet
By the way, if your clients really insist on a true invisible
setting, you might wish to try and dissuade them. Most of the jewelry
I’ve seen out there these days from commercial firms which are
invisible settings, aren’t worth crap. It’s not so hard for a
manufacturer to get fine looking invisible set work out the door.
It’s another thing entirely to have made it well enough so it will
hold up. This is a difficult technique to master and do really well.
And stones have to be critically well chosen or cut specially, to the
required size. Very little leeway there. However, there are plenty of
craftspeople (judging by the number of firms who offer such goods)
who seem to be able to crank out lots of invisible set work which
doesn’t quite meet the standards one might wish. Trouble is, because
the inadequate fitting or slopping work is on metal that you cannot
see, there’s no way to tell. And once those stones start to loosen,
it’s often almost impossible to repair then short of just dumping a
bunch of glue over them (yuk). Even sizing these rings can be very
risky to impossible.
Don’t believe me? Buy one of those invisible set things from
Overstock.com (which are there for a reason, remember), and size it
down one size. Then wear it a week and see how many stones have
become loose. And then try to find a jeweler who can promise to
properly tighten them again and ensure their safety.