Jewelry Manufacturing

The jewelry arts date back thousands of years. Mankind has always had a deep fascination with beautiful things. Early man collected and crafted many natural objects for adornment. Feathers, sea shells, stones and other objects were treasured for their beauty, rarity, and mythical powers. The techniques and processes which transform these items into objects of adornment range in complexity from utter simplicity to hi-tech wizardry.

For the purposes of this article we will focus on modern jewelry manufacturing techniques, the kind widely used in the jewelry industry today. In addition to the modern standard techniques, there are a great many specialty techniques that are beyond the scope of this article.

We will focus on the following topics:

• CAD-CAM
• Lost Wax Casting
• Fabricating
• Hand Forging
• Laser Welding
• Stone setting
• Ring sizing
• Finishing

(Computer Aided Design/Computer Aided Manufacturing)

The computer revolution in the past few decades has radically changed the process by which most jewelry is produced today and opened up vast new opportunities for jewelry design. Creativity and efficiency have been put on steroids with the modern tools that jewelry artisans and manufactures now have at their fingertips.

Specially designed software programs allow designers to manipulate and experiment with limitless configurations, different sizes, shapes and setting styles, and to tailor and tweak the final design with extremely high precision. In addition, the software is capable of rendering photorealistic images of the eventual finished piece taking almost all of the guesswork out of what the final product will look like. The files created in the design programs can be fed directly into special machines that can mill a wax with a degree of accuracy never before possible, or to 3D printers that can actually “grow” waxes and create designs that cannot be accomplished by milling or hand carving.

(often referred to a simply ‘Casting’)

Lost wax casting is one of the oldest complex forms of jewelry making dating back thousands of years. In the modern version a wax model of the item is ‘invested’ in a liquid plaster material and allowed to dry and harden. A channel to the outside allows the wax to be ‘burned out’ and evaporated, leaving a void the exact shape of the original wax. Molten metal is poured in through the channel and a casting machine using vacuum and/or centrifugal force ensures the metal is evenly dispersed throughout the space for solid integrity.

After the metal cools, the plaster cast is broken and casting removed. What emerges is an item in metal that is an exact replica of the starting wax. The casting is then cleaned up and prepared for stone setting, finishing and polishing.

Early waxes were created by hand. Until very recently waxes were carved by highly skilled artisans. While this is still done to some degree today, most waxes are now produced using CAD/CAM

Fabrication is a process that avoids the casting process and involves creating a piece directly from metal parts. Those parts could themselves be created from raw metal or mass produced parts from a manufacturer. Or a combination. There is typically more soldering involved in fabrication versus casting where the entire item (or large portions of it) are a solid piece.

Precious metals have different working properties and therefore may be more or less amenable to fabrication. Platinum and high carat yellow gold are highly ductile metals that lend themselves particularly well to fabrication techniques.

Hand forging is a process of fabrication. The jewelry item is created from refined metal stock through various techniques including wire pulling, hammering, bending and otherwise manipulating the metal. Heat is generally used in the process thereby ‘tempering’ the metal which makes it denser and more ductile. The downside of hand forged jewelry is that not all jewelers do it particularly well. There tend to be asymmetries present in the finished piece, and like fabrication in general, there tend to be more solder joints involved (depending on the design). Because it is very labor intensive, it also tends to be a more costly process.

One of the more recent advancements in jewelry manufacturing is the process of laser welding of precious metals. This provides a way to fuse two pieces of metal together without the use of solder. This is preferable for several reasons. First, the junctions created by laser welding are stronger. It eliminates any color difference sometimes introduced by solder, which can reveal the line where the solder is applied. The heat generated by the laser is precisely targeted, making it unnecessary to heat up surrounding areas of the piece with a torch in order to get solder to flow. This makes it possible to do many tasks with the laser without having to remove and reset gemstones, saving time and risk of damaging stones or weakening prongs.

Laser welders can also be used to perform fine repairs such as fixing areas of porosity in metal without having to flow solder into the voids. Another wonderful use of the laser machine is engraving. Not only hallmarks and purity stamps can be quickly inscribed on jewelry items (usually inside the shank of rings), but practically any symbol, logo or message. This is a great way to personalize a piece of jewelry.

Jewelry manufacturing involves a wide variety of setting styles and each one requires different skills and techniques. From basic prong styles to bezels to pavé, the choices are many. It is common to find jewelry styles that incorporate different setting styles to create different effects in the various design elements in the piece. Even something as basic as a prong setting can have multiple variations such as round, square (sometimes called ‘tab’) , or claw style. Split prongs are another variation, and then there are the number of prongs which can change the overall look of a piece.

With most settings the jeweler will cut a ‘seat’ near the top of the prongs for the girdle of the diamond to fit into. The tips of the prongs are then pressed down on the crown of the diamond, and then burnished to ensure the stone is securely set.

Sometimes prongs can be strategically placed to conceal imperfections.

One of the most common ‘repairs’ that is likely to be done during the life of a ring is sizing it up or down for a better fit. Sizing up involves expanding the circumference of the ring, usually by adding a piece of metal. Very minor sizing can sometimes be accomplished very easily and quickly by ‘stretching’ the ring with a special tool. The use of this technique is severely constrained by the thickness of the shank, type of metal, and whether there are small diamonds in the shank vulnerable to being dislodged by this process.

Sizing down almost always involves cutting the ring and removing a small piece of metal, then soldering or welding the ring back together.

Another popular technique for adjusting the fit of a ring that is slightly too large is the use of sizing ‘beads’ or bars. Small pieces of metal are soldered to the inside of the ring in pairs at the bottom of the shank. The beads slide over the fatty part of the bottom of the finger. This technique is used to overcome problems with enlarged knuckles and/or to stabilize rings that are top heavy and have a tendency to turn on the finger. Sizing beads or bars can also be used to adjust the fit of an eternity band that may not be possible to adjust otherwise.

The final phases of jewelry making involve polishing and sometimes electro-plating, as well as applying any millgrain or other textures such as a Florentine, brush or satin finish to the metal. Most mountings undergo a pre-polish before diamonds are set in order to prepare the piece for final polish. Often this is done in a tumbler which can smooth out some of the areas that might be difficult or impossible to reach by manual polishing.

After the surface has been pre-polished or otherwise prepared, final polish is done on a polishing wheel with brushes charged with a polishing compound.

Electro-plating of white gold is done as a final step. The item is submerged (sometimes referred to as ‘dipped’) into a solution containing rhodium (a lusterous white platinum group metal). An electric current runs through the solution causing the platinum to come out of solution and bond on the surface of the ring. It will only bond to metal so it is safe to use with diamonds and most gemstones. Areas that may not be intended for the rhodium to bond can be masked with a special paint before dipping. The layer of rhodium applied in this process is very thin and the process takes only a few minutes to fully coat the item with a bright protective shell.