Fabricating a Platinum Three Stone Ring

Part I

Tom Weishaar

 

 

1.  Recently a woman brought in her old platinum ring with a loose marquise diamond to be worked on.  After some debate she decided that it would be better to reset the 1.33 ct. diamond with an updated new three stone mounting.  She picked out a matched pair of trilliants to go on either side of the center and the job came to my bench for fabrication.  Fabricating a three stone mounting is one of the three requirements for becoming a JA®, Certified Master Bench Jeweler™ and is the project that seems to give bench jewelers the most difficulty.  I thought I would describe the process I use, but it will require three separate articles to complete the complicated process.  I hope you enjoy this series.

 

2.  In part I of this trilogy, I will fabricate the platinum shank for my project.  A size six ring requires 60 mm of 3mm square stock to complete.  I’m starting with 2 inches (or 50 mm) of stock, but I will reduce the center to avoid filing away the shank.  I start by locating the center of the piece of stock and marking its position.

 

 

I want to reduce the center section from 3mm square down to 2mm.  To help me visualize where to roll the metal I am marking a center zone of metal (approximately 20mm) with a black Sharpie.

 

3.  I slide the stock into the reduction gears of my rolling mill and clamped it down tightly.  I can now roll the metal back and forth over the center section tightening the mill with each pass.  The black ink helps me see where to stop and then reverse the mill. 

 

When the rolling is complete my stock is now 60mm long.  Both ends of the stock are still 3mm square, but the center section has been reduced to 2mm square.  The rolling has saved me the expense of needing to use a longer piece of platinum and the time it would take to file the center down to the correct thickness.

 

4.  This tool is an antique shank bender.  If you ever come across one at a flea market or on E-bay they are handy for bending a piece of thick metal into a nice circle.  In this picture I am using a size 6 die and bending my stock into a perfect ring.

 

 

 

 

5.  This picture needs a bit of explanation.  I like to use some modeling clay to approximate the curvature of the finished ring.  By placing these three rather large stones in the clay I can visualize the correct angles of the stones and their relationships to each other.  I want to tuck the side trilliants up under the center stone and angle then down toward the finger so that my completed ring will not be too wide.

 

6.  In this picture you can see that the three stones will have a total width of 17mm.  That is the maximum I can allow for a size 6 ring.  This process, the “layout”, is very important in the planning of a custom mounting.  If I skipped this process then I would lose control of my design and the ring could turn out badly.

 

 

7.  The classic three-stone ring has a recessed center section and two “wings” that come up to hold the side stones.  To achieve this look I like to mark a line that splits the thicker top of the shank into two 1.5mm sections.  The purpose will become apparent in the next few pictures.

 

 

 

Fabricatin a Three Stone Ring continued