Opal Ring

This was my first attempt at a stone setting project. I got it wrong repeatedly, but unfortunately didn't take enough photos, instead making it look like I knew what I was doing!

I started off making a bezel to hold the stone. I was particularly lax with the photos during this stage. The wall is made from 0.5mm thick sheet. There are actually two bases, because I ruined two previous attempts due to filing through their overly thin bases. There's a 0.9 base inside the wall, then that wall/base combo was soldered on top of a 0.7mm base. Firstly I made the wall:

  • I measured the circumference of the opal. I used a piece of electronics solder as a higly deformable ruler.
  • Then cut a strip of 0.5mm sheet to form the wall. 4mm high, circumference+bit long.
  • Finally, bent strip into rough circle and solder closed.

Then the base:

  • Temporarily attached opal to 0.9mm sheet. I used a tiny piece of blu-tack.
  • Drew around it with marker pen
  • Pierced out the resultant oval shape. I deliberately cut slightly oversized
  • Carefully filed the edges until only a hair-thin trace of marker pen remained.

I then repeatedly test fitted the base into the wall, filing where necessary to get a perfect fit. The perfect oval shape of the base corrected the rough shape of the wall. With patience an almost light-proof fit was achieved. It was then soldered with hard solder.

I made two bezels this way, assembled them into rings, and destroyed them at the filing/polishing stage. The bases were just too thin.

So I repeated it a third time and then soldered the whole bezel assembly to a 0.7mm sheet (I wasn't taking any chances this time!). This made a total base thickness of a rather chunky 1.6mm. After filing it thinned down, of course, and I quite like the finished size. After soldering it to the 0.7mm sheet, I pierced it out and filed out the protruding edges to meet the bezel wall.

Here is the finished bezel after a light polish with 1200 grit wet & dry

You'll have to believe me when I say no joints were visible, the picture quality ain't great.

Now the photo frequency increases as I started the ring part. The ring is made from 3.2x1.6mm D - profile stirling silver wire. The D shape is, of course, so that it sits flat against the finger and is nicely rounded on the outside.

I set my caliper to the desired internal diameter of the ring, 16.5mm. This later turned out to be the wrong size, but that's another story! If you decide to make a ring, get this bit right! A mark was put on a tapered ring mandrel at the required diameter

I annealed a length of D wire by heating to what is universally described as a "cherry red" colour, and quenching in water. I then pickled it to remove oxide. One may quench straight into pickle to speed up the pickling process, but it is not recommended because hot acid can go flying around. When I get lazy I do it, but carefully. Annealing makes the silver more malleable.

The wire was then hammered around the mandrel with a rawhide mallet. It is important to hammer just beyond the point at which the wire is tangent to the form. This gives a nice uniform curve. Lots of small taps and slow feeding is the way to go.

I needed one hand to take the photo, but you get the idea. The formed ring follows.

Note I left a decent amount of overlap. I then cut it with a medium piercing blade:

The closed ring. Note how well the ends line up - the result of careful hammering and choice of place to cut.

 

Soldering the ring with hard solder.

 

I soldered the ring closed at this stage so I could hammer it on the mandrel to achieve a perfectly circular shape. I don't think this was really required, but I did it anyway. I annealed it again to prepare for more hammering. Note the colour at annealing temperature.

The ring after soldering, pickling and hammering on the mandrel. I tried to hammer equal amounts with the ring on the mandrel in both orientations, to avoid tapering the inside.

Then I measured and marked up the cut to accept the bezel.

I made the cuts with a medium piercing blade, and carefully filed a curved profile on the ends to match the shape of the bezel. Here's the bezel test-fitted in place:

The two parts ready for soldering.

Then there was a massive digression. Holding these two pieces together was exceedingly difficult. I tried elaborately shaped binding wire contraptions, but they failed when heated; deforming slightly and leaving the bezel askew. I ruined a further two ring attempts this way! I decided the solution was lightly spot welding the pieces in place. The weld could easily be broken and remade repeatedly until the correct alignment was achieved. I made a capacitive discharge welder out of a pile of 25 63V, 2200uH caps wired in parallel. They are charged slowly from a bench power supply, then discharged rapidly into the workpiece via a very chunky thyristor triggered by a footswitch. The energy storage goes with the voltage squared. At 60V it was a formidable beast, capable of welding coins together!

The welder

Foot activated for hands-free (or rather hands-holding-the-workpiece-together) welding. 

 

Some coins welded together

I held the bezel in one crocodile clip and the ring in the other, and buggered about trying to get them lined up. It took about 20 attempts to get it perfect, but each attempt was a simple 1 minute process of charging the bank, lining it up, welding, inspecting and snapping the weld. The welds were performed at 40V. I only welded one side so that I could bend the weld slightly if it was only slightly off.

Here's the perfectly aligned ring 

 

I pickled it to remove the welding oxide, added flux and a pallion (blob) of solder: I used medium solder so the bezel didn't fall apart (recall it was soldered with hard solder).

Soldered on one side and pickled

I added a bit of binding wire to pinch the other side into contact with the bezel. It was soldered in the same way as the first side.

Finished ring soldered and pickled, ready for setting and polishing

I filed the top of the wall to thin it and create a nice bevel ready for stone setting. I also filed the harsh corners of the bottom of the bezel to make it attractive and comfortable.

Ready for setting

Set. Note the bezel rocker I used in the background, next to the binding wire. 

I burnished the rough set edge with a pointed burnishing tool. I prepolished with 1200grit wet & dry.

Finally I polished it. That's "Goddard's Long Term Silver Polish" on a cotton sock.

Beautifully modelled by yours truly

I am most proud of the reverse of the bezel.

I found this project quite a challenge. My repeated attempts at it became something of a house joke. The two main problems were inferior holding methods prior to the spot welder, and obsessively filing the back of the bezel towards perfection until I filed straight through! The solutions were, of course, a spot welder and a thicker base. I made the base from two sheets, but one thick one would have been better. I just lacked the material.

The repeated attempts were worth it, however, it's one of the few things I've made with which I have been completely happy. It's as close to perfection as I think I could get. 

 

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