We have had positive feedback of our repair/custom shop visible from the showroom. I have great response regarding this blog. We have found that people are genuinely curious and interested in what happens at the jeweler’s bench.
After watching some videos on sharpening my goldsmithing skills, I thought how cool it would be to have a bench monitor for our customers. My Mantis bench microscope, that I love, has an awesome big brother that is outfitted with a webcam. That would be nice to have, however, it is $2500, so that is not happening any time soon. My solution: I took an old laptop and dedicated it to a good webcam and ran a wire through the wall to a monitor in the showroom. The WebCam is aimed towards my bench pin and covers a pretty good viewing area of where all the action takes place. When jewelry is brought back to me for inspection, the customer can see how I am poking and prodding, checking for loose stones. They can watch me, from a close up perspective, tightening their stones. I can even press record and document the entire inspection including audio.
side notes: I do not have a live feed of the microphone to the show room. My singing would surely drive away customers.
Also found it frustrating that the Logitech C920 webcam software does not support a full screen view. I found free third party software to fit the bill.
24 karat gold is pure. (99.9%).
Jewelry is mainly alloyed to 18k (75.0%), 14k(58.5%) and 10k (41.7%).
In the Middle East and India you may see high karats like 21k. In Great Britain you may see 9k.
Jewelry can be stamped as karat or expressed as a percentage.
24k 999 (99.9%)
18k 750 (75.0%)
14k 585 (technically 58.3%. However the Italians made a “plumb” alloy promising at least 583. So now we have 585)
SIDE NOTE ON STERLING SILVER
Sterling silver is 92.5% silver and 7.5% copper. Sterling Silver is commonly stamped 925 (92.5%)
DIFFERENT WAYS TO PUT IT
If you had 12k gold, you would have half gold, half other metal. (12 is half of 24). 18 is 75% of 24. 14 karat gold is 14 parts gold 10 parts something else. 10k is 10/24ths gold. It is all relative to a number system of parts of 24.
MIXING METALS. ALLOYS.
14 karat gold, regardless of it’s color is about 58.3-58.5% gold. The remaining percentage, is other metals that change the color, melting temperature, hardness, malleability and other characteristics of gold. A typical yellow gold alloy today would consist of gold (58%), silver (25%) and copper (17%). In Europe, older pieces of jewelry often have a slight rosier color. Their “recipe” for 14 karat yellow gold had a slightly higher copper content and lower silver content then most modern alloys giving them a pinker hue. If you were alloy gold with aluminum, you would get a purple colored metal that is brittle.
[Photo from Meevis.com]
WHITE GOLD. AN OXYMORON.
Before World War II jewelers worked primarily in gold, silver and platinum.
But during the war, the US government declared platinum a strategic metal and banned it for civilian use. Copper was also needed for the war effort so the US mint used steel to coin the pennies in 1943.
So Jewelers, stuck without a durable white metal, alloyed gold with nickel to “bleach” out the golden yellow metal.
That alloy does have a nice white appearance, however, it is not ideal to work with. It takes the whiteness of nickel but also takes the hardness of nickel, reducing the workability of the metal. Today’s typical white gold alloy still contains nickel, but just a lower percentage.
The common white gold alloy today has better malleability, a lower melting temperature for improved casting and is much softer then the high nickel alloy. However, as a draw back, the modern mixture is not very white. White gold jewelry today is often rhodium plated to brighten it up. Rhodium is in the platinum family of metals. Rhodium plating is fairly durable. Jewelry can be refinished and replated with rhodium to freshen it up.
Here at Atlas jewelers, we do our own casting. We chose a nickel/palladium white gold alloy that is white enough to not need rhodium plating. It is a bit harder to set stones, has a slight higher melting temperature and costs a little bit more, but the results for the wearer is superior.
Here is a GRS benchmate modification that has really helped me save time. I made a mini wood bench pin to cover the metal hand rest that comes with the Benchmate system. I have been using the metal brace for a quick cut or support for drilling. But a wood bench pin is much better for that. I used a scrap 1/4″ strip of hardwood. Cut out some notches for a screw and wing nut to attach it and a few odd shape cut in the front for saw piercing and filing.
If I have a job more suited for a sturdy bench pin, I switch out the ring holder for the quick-change pin. But this is a nice, time saving addition so I don’t have to.
Because we do custom work, I explain the casting process all the time. The whole thing from front start to finish is very interesting. However, It is a long procedure with a lot of down time between steps, so it is something the customer can not just stick around to watch. Multiple pieces can be cast at the same time. But for this demonstration, we are doing one.
Most jewelry starts here. Pieces that are mass produced or duplicated usually starts with a carved wax, even though there are situations where you might make the original directly in metal by fabrication. We still hand carve most of our waxes but for some intricate pieces we have CAD (computer aided design) produce a wax. Shown here is a 4mm wide knife edge band with a carved head for a modified radiant cut diamond.
A metal cylinder, corresponding in size to the base, is added. By formula, a specific amount of water and investment (a special, fine plaster) is mixed then vacuumed in a chamber to remove bubbles.
The cylinder rests for an hour for the plaster to harden. Then we remove the rubber base to expose the end of the sprue and it is placed in the kiln, sprue side down.
OUR CASTING ROOM
We have a computer controlled kiln that we programmed to come on at midnight and slowly takes the oven up to 1350 degrees in ramped stages and brings it back down to about 900 degrees (cylinder casting temperature) at the time we arrive the next morning. What happened over night was, as the kiln temperature raised, the wax melted out, leaving a cavity of exactly what we carved.
We basically pour the molten metal into the cylinder down through the sprue into the cavity of the mold. Actually, we force it in with a centrifuge. But you get the idea. Some people use a vacuum to assist in getting the molten metal in the mold.
The plaster is broken away and the what remains is the rough casting ring with its button. To cast the 7 gram ring, we used about 21 grams of metal. The extra metal helps push the metal into the mold and is needed. The sprue button can be used in the next casting, so it is not waste.
Shown here is ring with the sprue cut off. The shank has been burnished, sanded and is ready for stone setting and then polishing. At this point the ring the ring is a one- of-a-kind. To make it again I would have to carve a new wax. A second option is to make a rubber mold of this original. The rubber mold can be injected with a molten wax injector to make additional waxes for additional casting.
This method takes a little bit longer, however, the results are much better then just sanding out blips. Another bonus is that burnishing the ring “work” tempers (hardens) the metal so it scratches less for the customer.
On our custom pieces, after casting, we beat the surface with the burnishers to harden them. Especially the shanks of rings. This works great on sterling silver. Burnishing with the bent burr also can get rid of porosity.