Going custom: The rush of fabrication

by charlene_voisin | December 1, 2013 9:00 am

By Tom Weishaar

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Editor’s Note: This is the final instalment in a six-part series on creating custom jewellery.

Author’s Note: I’ve spent this past year sharing my techniques and reasons as to why I enjoy being a custom bench jeweller. I hope my articles were able to convey the satisfaction and pride that making jewellery has brought to my life. I am going to use this last article to announce I am retiring as a bench jeweller. Next year will mark my 40th year on the bench, and it’s time for me to step aside and allow some younger eyes to take over. I want to thank everyone who has followed this column for the past five years. It has been a pleasure sharing my techniques and reasoning with you.

In a normal week, I am given four potential custom pieces for which to work up estimates. Typically, customers approve two out of the four projects. My job is to create them as best I can, while at the same time, being mindful of my customers’ budgets. If you follow this column, then you have seen the great economic benefits of using CAD/CAM for helping to keep the cost of custom designs down. While I like using this particular piece of technology, fabrication will always be my first love.

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This past August, the design for the three-stone platinum ring seen on page 1, along with the diamonds to the right of it, were given to me for immediate delivery.”¨ I didn’t even need to do an estimate, which was unusual. The centre stone was a 3.96-carat oval, while the side trilliants were .70 carats each. These were very high-quality and expensive stones—they demanded attention. That said, I was more interested in the single word written at the top of the job card—’RUSH.’

For most bench jewellers, the word ‘rush’ means ‘now,’ ‘fast,’ or ‘get it done.’ If I used CAD/CAM for this piece, it would take a total of two hours’ labour (spread over two days) to design and grow; sending the piece for platinum casting would take eight days’ turnaround time. Finishing the mounting and setting the stones would likely take about five hours. From start to finish, I estimated seven hours spread out over 10 days.

Ten days is not a long time to wait while having an expensive ring made, but I do have another option. I can fabricate this same ring in two days, although labour time would take 16 hours. At $100 per hour (retail), that’s a substantial increase in the cost of making the ring. In the end, I presented the pros and cons of both options to my employer, who decided to strike while the iron was hot. I was given the green light to fabricate the ring and the store would absorb the additional labour cost. The oddities never end.

Finally fabricating

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During the 1990s, the three-stone ring was the height of jewellery fashion. De Beers had done a fabulous job of promoting the design concept of a ‘trilogy’ ring representing the past, present, and future of a relationship. In that decade, I fabricated approximately 150 three-stone rings. This particular style of ring was so popular that Jewelers of America (JA) included it as one of the designs a candidate must fabricate to be certified a master bench jeweller. It had been so long since I fabricated one of these that my heart literally leapt with joy upon getting this job. Hurrah! I was going to fabricate again.

About the time I began fabricating three-stone rings, our store purchased several from a high-end manufacturer. Each of the pieces was unique and beautifully made. I spent hours studying how they were constructed and tried to imagine the processes the jeweller used to create them. At that point in my career, I was more concerned about getting the technical aspects correct than the esthetics. It was not until after I had constructed about a dozen rings of my own that I began to relax and concentrate on styling.

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I always begin ring projects by building the crown for the centre stone and working out toward the shank. Following the design, I constructed a standard”¨four-prong crown with upper and lower gallery supports, also known as rails, as recent terminology would have it. The centre diamond measures 12.74 mm x 8.76 mm. I prefer starting with the upper gallery support. This is made by forming a stick of flat platinum wire (i.e. 1.5 mm x 1 mm) into an oval shape that is approximately 10 per cent smaller than the diamond’s diameter.

Always be aware of where you position the solder seam in the supports so they are not visible. With care, the seam will end up under one of the four prongs.

Once formed, the wire supports are soldered together using ‘1700’ platinum solder. After soldering, both upper and lower supports are placed in the bezel forms and lightly hammered in place. The forms come with tapering steel mandrels that help push the platinum into the exact oval shape required for this design.

I prefer making the lower gallery support slightly taller than the upper (i.e. 2 mm x 1 mm). Personally, I feel that weighting the bottom gives the ring a visual lightness as the metal approaches the centre stone.

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After both supports have been made, it is time to position the main prongs for the centre stone. Great care needs to be taken here. For this design, I needed to create a double-prong look between the centre oval and the side trilliants, which have a slight cushion shape so their corners fade away from the oval. To achieve that, I matched the main prong positions so they lined up with the secondary trilliant prongs.

Recently, a young bench jeweller asked me if there was a ratio between prong diameter and the size of the stone they are holding. The answer I gave is, “Yes, and I wish I knew what it was.” I was not trying to be flippant with my remark, as it is obvious we use larger prongs to hold bigger diamonds. It’s just that there is no accepted standard for this ratio. I normally use 0.80 mm (20 ga.) diameter for stones up to .75 carats, 1 mm (18 ga.) for stones up to 1.50 carats, and 1.25 mm (16 ga.) for stones more than 1.50 carats. I also like to use wide, though thin prongs, that I split for stones with corners, such as cushion cuts.

In the photo below, I am using a Kraus bur to cut grooves in the gallery supports for the prongs. This procedure creates a lap joint. I do not like the appearance of prongs simply butted up and soldered to the outside of the supports. Butt joints require more solder and are not as strong as lap joints.

Soldering platinum items together used to be very difficult due to the high heat required. Since metal tools could not be used to hold the parts, jewellers would carve all sorts of niches into ceramic blocks to hold them together while the first few solder joints were being made. That all changed with the invention of the laser welder. This tool is perfect for lightly tacking parts together in inconspicuous places before soldering the units. The laser makes it possible to create multiple solder joints at one time. I also like to tack small pieces of solder into the inside seam between two parts and then use a torch to pull the solder to the outside. This method practically ensures a pit-free solder joint.

Phase two—side crowns

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With the centre crown now complete, it’s time to turn our attention to the crowns for the trilliant diamonds. I prefer to use a ‘cut and fold’ method for making supports that come to points, such as a triangle, square, marquise, or pear. This requires a very accurate measuring of the stones. Next, I deduct approximately 10 per cent from the stone size so the supports will be smaller than the stones. The new measurement is then transferred to my stock, which was 1.5 mm x 1 mm. My goal is to create two triangular supports that won’t be visible when viewing the ring from above.

I used a saw to cut a groove halfway through the metal, followed by a square file to open a V-notch in the groove. As the metal was folded, I reused both the file and the saw blade to carefully remove metal from the notch until the stock folded together in the tight seam. It is necessary to anneal the metal several times during the folding process. Just as in sizing a ring, it is important not to have gaps in the seams if you want to avoid pitted solder joints. I used ‘1700’ platinum solder for the two upper gallery supports after folding them tightly.

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We can see in the photo to the right that the three-stone ring is starting to take shape. These side crowns were soldered in place using ‘1600’ platinum solder. Note how every surface is either polished or sanded to a 1000-grit finish. This is the ultimate beauty of a hand-fabricated piece of jewellery. Each section can be finished prior to assembly, allowing you to end up with a flawless look.

When setting stones with points like trilliants, I prefer to use chevron prongs where possible. I believe this type of prong offers the greatest protection for fragile tips. I also think they look better than standard round wires. I made the chevron prongs for this ring by taking 2-mm square stock and cutting a flat side on one half. Next, I used a 90 degree Hart bur to cut a groove down the length on the now triangular stock. This grooved piece of metal was then cut into two pieces, mitered into the ring, and soldered in place.

Phase three—making the shank

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To create the ring’s shank, I began with a 2-in. length of 3-mm square stock. This is actually too thick for the shank’s lower portion, but I needed the thickness for the upper section. I marked the metal and then used the rolling mill to reduce the thickness in the middle. As a rule, I like ring shanks to be less than 2-mm on the back side and between the fingers. Thick ring shanks are heavy, expensive, and uncomfortable to wear.

The antique tool seen in the photo to the right is called a shank bender. It has an off-set cam that allows you to insert a metal blank; a quick tug on the handle rotates the mandrel into the corresponding form, bending the metal into a ring shank. The same can be achieved with shank-bending pliers, but the shank bender is easier on the hands and does not dent the metal. Heavy-duty cast iron versions of this tool are no longer in production, but they do occasionally appear on Internet auction sites. They are a great buy if you can get one for under $100.

Partway through fabrication, I decided to change the shank’s design. If you look at the original drawing, you can see the shank is heavy in appearance. Since the ring design has traditional upper and lower gallery supports with a space between them, I decided to carry this element through to the shank. I slit the metal with a saw and used a prong lifter to elevate the shank’s upper leg. Visually, this will lighten the look of the shank. Once all the rough shaping of the shank was complete, I filed it, sanded it to a1000-grit finish, and in some spots, polished it to its final form. I prefer to ensure everything is perfect before final soldering.

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I’d like to use this final project to discuss soldering platinum. Firstly, all the images of soldering in this article were taken when the metal was still relatively cold, otherwise I would have needed a dark filter on the camera. Platinum solders flow in the range of 1600 C to 1700 C, or roughly 3000 F. Jewellers need to wear number ’10’ (or higher) welding goggles to protect their eyes from the ultraviolet light emitted by the glowing metal.

Also, do not use flux or fire coating when soldering platinum; it is a pure metal that does not oxidize during soldering, so no coatings are necessary. Flux—which we know melts in the same temperature range as gold solders—is absorbed into platinum at high heat and can break down the bonds between the grain boundaries.

This ring was constructed using a combination of ‘1600’ to ‘1700’ platinum solders. Unlike gold or silver, platinum dissipates heat very quickly, which means you can solder very close to a previous seam and not be overly concerned with melting it. I tried to show how this ring was assembled using lap joints with good surface contact, rather than weaker butt joints. The amount of surface contact helps keep everything together during soldering.

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Platinum solders of 1500 C or lower are alloyed with palladium to bring down the melting temperature. I only use these solders (and never less than ‘1400’) when attaching lightweight platinum filigree into heavier mountings.

I think the platinum three-stone ring turned out well. The customer loved it and that’s what really matters. This job took a total of 16 hours to complete, including all stone setting. Fabricating this ring was a rare pleasure for me. It’s been a long time since I didn’t have to turn a computer on to make a ring.

As this is my last article, I want to thank my editor, Jacquie De Almeida, and all the wonderful staff at Jewellery Business for allowing me to be a part of the magazine for the past five years. I also want to thank the many readers who e-mailed questions and comments. Thank you all for your support.

[11]Tom Weishaar is a certified master bench jeweller (CMBJ) and has presented seminars on jewellery repair topics for Jewelers of America (JA). He is an award-winning columnist, picking up Silver at the Kenneth R. Wilson awards for his six-part series on stone-setting techniques.

 

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