How to Inlay Jewelry

When I first started inlaying, I used an old wet lapidary machine arbor with worn trizact belts. I was getting sub-standard results. The drums were very old and the machine would rattle around which gave me an inconsistent straight edge for grinding and polishing. This is important to consider because I wanted to make nicer detailed inlay. Once a piece is inlayed, there is much to consider, such as multi-stone polishing and polishing stones next to different metals such as silver or gold. In my opinion, cabbing is far easier than inlaying, because you are only grinding and polishing a single stone without any metal around it.

I also started inlaying hand carved channels which were not symmetrical which is a pain in the neck, making the inlay process more difficult. A good straight channel will make a noticeable difference, just as a perfect round channel is easier to inlay rather than an imperfect round channel. For round inlay pieces, I glue a small dopstick to the stone, then inlay with ease. For all other pieces, I use small instruments that feel comfortable with my grip.

Once I bought my first diamond 220 grit steel back wheel, I was inlaying cleaner and faster! You will find that diamond tools are superior to any other lapidary tools on the market. After years of working with this wheel, it still has a clean edge and cuts remarkably fast. You get what you pay for. A 220 grit soft back wheel comes in handy for fragile stones such as lapis lazuli and spiney oyster. When inlaying these stones, I use the soft back wheel first, and then gently touch them on the steel back wheel creating a flush and uniform straight edge. These diamond wheels work well on most lapidary arbors.

For more detailed work I found that working with polypads, crystalpads, and small leather wheels with variable widths on the handset work very well. I use diamond mesh starting from 600 grit to 3000 grit with these pads for most stones. Between each step I clean the stone and make sure that I do not contaminate the pads as well as my work area. I mostly use these pads after I finish stones with the big diamond wheels before inlaying. This method makes the jewelry much nicer yet there is more skill involved. When I finish a stone before inlaying I bring it to the 1200 grit with a slight cab. I make sure that when I do inlay the stone that I do not get epoxy on the finished surface. Once the stone is set, I use a 1200 grit leather wheel followed by a 3000 grit polypad. (For all flat surfaced mulitstone inlay, I use a lap charged with sapphire powder). For this method I will use a soft leather wheel charged with sapphire powder on my handset.

When finishing opal I notice that any type of contamination or minute mistakes will show up on the finished surface. I make sure that before I set an opal that the surface has a fine polish and that the back of the stone needs to be ground to the desired depth. In some cases, there are traces of epoxy on the surface of the stone. This can be easily removed with a 1200 grit small leather wheel (you must make sure that the wheel is always square and that it is cleaned before each use).

You can visit my website for more articles on lapidary techniques and other jewelry fabrication articles.

--Brent DeSantis--

My jewelry stone inlay consists of all natural gem quality Australian Black Opal, Lapis Lazuli, Black Onyx, Sugilite, Coral, Turquoise, Mother of Pearl, and Spiney Oyster.

There are four steps I abide by in successfully completing natural stone inlay:

1. Grading the gemstones
2. Carving each stone for a channel within the piece of jewelry
3. Correctly bonding each stone to the very bottom of the desired jewelry channel
4. The final polishing of the gemstones

After each inlay step, the stones are carefully inspected for fractures, cracks, and inclusions. If any of the aforementioned is detected, we will remove the stone and repeat the process.

-Grading
Each gemstone is carefully graded where there will be no calcite (white patches) in our lapis, no black matrix patches in our sugilite, no pits or discoloration in our Coral, etc.. As for my natural opal inlay you will see that each stone displays a generous play of color ranging from blue-green to yellow-red flashes (this play of color will determine the overall price as well).

-Carving
When you carefully look at my inlay, you will notice that it is very high quality. There are no gaps, only uniform design and symmetry when inspected from all angles. A good representation of symmetrical inlay would be the Yin-Yang jewelry inlay.

-Bonding
Once a stone is ready to be inlaid, it is precisely bonded with an indusrial strength 2-part epoxy to the bottom of the jewelry channel. Provided that all the stones are securely set, there are no traces of epoxy on either the metal or stones.

-Polishing
The most important and last process is polishing the stones. I make sure that each and every stone that is inlaid has a nice high polish. There will be no scratches, just high polished gem quality inlaid stones. As for opal, I hold on to a finished opal inlay piece for months, sometimes years before displaying it for sale to make sure no crazing or cracks occur.

When drilling holes into stone you must have the right tools and equipment. The most important machine that I use is a mini drill press which has variable speeds and is more stable than drilling with a handset. For every hole that I drill, I always drill a pilot hole with my smallest diamond drill bit, then the next size bigger until the desired drill bit is reached. This small pilot hole allows bigger diamond bits to effortlessly drill into the stone. One reason why a diamond drill bit doesn't cut into stone effectively is caused by stone build up on the diamond bit and lack of water. I clean my diamond drill bits with a white diamond cleaning block soaked in water all the time, this will surprisingly increase the life of your diamond bits. When drilling, I get a feel for the stone and repeat an up and down motion while lubricating the stone with gem lube and/or water. After I drill the holes, I lightly steam clean the holes with a steam cleaner on low steam. It is rare that my stones have imperfections after being inlayed. If this is the case, I will drill a hole into matrix in turquoise, pits in spiney oyster, or chips in other stones. This method that I use works well for multistone inlay, and makes the stones more attractive and clean. The only reason why I drill holes into stone is so that I can inlay a piece of silver or another stone into the drilled hole. I mostly use stones and different gauges of silver wire depending on the size of the hole that is drilled.

Unlike other gemstones natural opal does not have a crystal structure, and the texture consists of amorphous silicon dioxide having submicroscopic silica spheres. Depending on the size and how these silica spheres are arranged together determines how they diffract light. These silica spheres have diameters that range from 0.15 to 0.30 microns (one thousandth of a millimeter ) which is a little smaller than the wavelength of visible light which ranges from 0.4 to 0.7 microns in diameter. In order for opal to be considered precious opal the silica spheres must be uniform in diameter and arranged in neat rows. A precious opal that has flashes of red will also contain all the other colors of the spectrum as the opal is seen by all other angles. It is interesting to know that this structural color of opal is produced by light, conveyed by the eye and is then understood by our minds.
To this day I am fascinated on how challenging Natural Opal is to cut and polish. Since I know that Opal with flashes of red and yellow are highly prized, I do my best on keeping as much of these colors as I possibly can into an opal cabochon or incorporating it into my inlay designs. Generally, if I am inlaying natural opal I will design the jewelry around the stone so there is minimal cutting of the opal. I never know what the stone will look like until it is finished. As I get more experience grading opal, all other types of stones that I work with become naturally easier to work with. I realize that all types of natural opal are magnificent gemstones and display unique characteristics. But out of all the natural opal in the world there is only a couple types of opal that I am comfortable in using.
The most prized natural opals that I use for my inlay jewelry is natural opal from Australia and Brazil. Both Australian and Brazilian Opal have a very good reputation for producing some of the most stable and precious natural opals in the world. These opals are similar in both their flashing colors and the intensity of the play of color. All natural opal has a Mohs hardness that ranges from 5.0 to 6.5 which are considered to be softer stones. Suprisingly, Brazilian Opal is hard to distinguish between opal from Andamooka, South Australia. They both have a similar hardness and contain the same play of color with a light background.

Brazilian Opal mainly comes from the Boi Morto mine. Boi Morto means "ox dead" in Portugese. This name came from an ox that fell off a cliff and died at the base of the opal occurrence during early opal prospecting of the area in the late 1900's. This Boi Morto Mine is around the area of Pedro Segundo (Pedro II), which is a small town in the state of Piaui', in Northeastern Brazil.

The Australian opal that I use, mostly known as Black precious opal, comes from Lightning Ridge in New South Wales, Australia. This type of natural opal has a very distinguishable look compared to other types of opals. This stone was given the name Black Opal due to the stones dark background color. It is like a colorful rainbow flashing light in front of a black night sky. Black Opal from Lightning Ridge is considered the rarest and most prized opal in the world. After working with this magnificent gem, I found that it is more stable than most types of natural opal.

I purchase these types of natural opals in small parcels of opal rough. Each opal nugget has clay coatings and potch (common opal) around the lines of fire. This needs to be either ground or cut to expose what is inside each piece of rough. Once the lines of fire are partially visible they can be graded and classified into certain categories such as cabochons or inlay pieces.

When finishing opal I notice that any type of contamination or minute mistakes will show up on the finished surface. I make sure that before I set an opal that the surface has a fine polish and that the back of the stone needs to be ground to the desired depth. It is common for other jewelers to mix dark dye with the epoxy to give the opal a better brilliance of color. I will use the same method but it depends entirely on the stone that I am inlaying. When I set a rare Black Opal into a deep channel there is no point in enhancing the color with dye. If you are interested in Natural Opal, then why not be interested in the finest opal in the world?

Over the years I have found that most natural opal inlay jewelry is basically garbage. The reason is that the amount of natural opal that is inlaid is very little. This technique in opal inlay baffles me even to this day. It is the highest form of trickery I have ever encountered in jewelry making. This type of inlay tends to be a problem because what is left of the opal cracks very easily or even falls out. The method of using epoxy and black ink or paint is often used to enhance the colors of the opal. So the opal looks much nicer than it actually is and the epoxy is weakened by the black ink. Most of the time what is inlaid is a very thin piece of opal like that of a doublet or even a triplet.

I have much experience in working with Natural Opal jewelry repairs, and now I will never do it again. I just think that it is not worth it. My method of natural opal inlay can be very different than other jewelers and I only prefer my method of inlay.