Easy Guide by Tony Thurber

Several years ago Rock and Gem published a 'how to' article about my opal inlay pendants and earrings. Since then, the process has been refined and improved.

The object is to create a simple, organic, complementary setting for an outstanding piece of opal. All my work involves opal; although the techniques work equally well with other materials. The equipment required is basic for any hobbyist: a saw or two, a 6-wheel lapidary set, and a Dremel or similar hand piece. The blades, grits, and burrs will be listed below.

The first step is of course to acquire raw materials. Rough opal is now available at Tucson from more than 50 dealers. Avoid opal in water or with high water content; as it is prone to crack. Above all, keep any opal out of safety deposit boxes, which are desiccated to preserve the documents. Desiccation is death to opal. Host material can be virtually anything with a hardness similar to opal (6.2-6.5). Softer material tends to undercut, fails to take a crisp inlay margin; and may not hold a polish. My pieces are made with Quartz, Jadeite, Chalcedony, Chrysoprase, Limbcast Agate, Jasper, and Petrified Wood.

Slab the chosen host material to about 3/8" for pendants and 5/16" for earrings. Carve the host to the preferred shape and size with a 4-4 1/2" turbo diamond saw blade (a Home Depot item) and bevel-cut the corners except where the 'hanging hole' will go. Leave that area flat. Grind the piece to the desired shape and curvature on the most aggressive wheel of the lap set (60-80 grit). With an aluminum pencil, scribe an outline of the inlay hole to be excavated.

Excavation requires the use of four diamond burrs of different shapes, sizes, and grits. Those I use appear in photo 1, and figs. 1-4, in the order to be used.

• With burr No. 1, excavate near but not quite to the scribed line. (Fig. 1)
• With burr No. 2, remove material from the curved bottom of the inlay hole: (Figure No. 2)
• With burr No. 3, undercut the banks slightly; (Fig. 3)
• With burr No. 4, straighten up the walls: (Fig. 4)

Pendants require a hole. Use a 2mm diamond core drill (Lasco) and drill transversely from opposite sides of the flat areas left on either side near the top of the piece during the carving and grinding process. Use an ultrasonic drill if you have one (I do. Get yours from Bill Ritter of Cutting Edge Solutions, contact info below). Otherwise, use any high-speed rotary hand tool. The Dremel, Lasco, and Foredom tools are fine, and far less expensive. To drill, use light pressure and lots of water. (Fig. 5)

With the hanging hole completed, enlarge it with a diamond bead reamer. (Right, Photo 1) Bead reamers are hard to find. Lasco doesn`t presently make them, but reamers will be available with the Lasco inlay kit which I use and recommend. Be slow and careful at this stage, working from each side alternately, with light pressure and using lots of water. At 16,000 rpm, excessive pressure or heat can literally blow the piece apart. Be careful.

Next, the gold. I use 18k that I alloy and roll out on a rolling mill to 1 mm x 1.5 mm for pendants and .75 mm by 1.0 mm for earrings. Make your own, obtain from a goldsmith, or from Rio Grande. The hand tools for this step include forming pliers, flat pliers, and an end cutter. All are pictured: (Photo 2)

Using fingers and forming pliers, bend the rectangular gold wire to fit the inlay hole, working clockwise from a starting point on a straight section. (Fig. 6). When completely around, overlap the remaining gold wire over it's beginning end. Score the cutting point with an Xacto blade (Photo No. 3), remove the gold, cut on the scored line with the end cutters; and work the ends into alignment with the flat pliers. Braise the gold ends together with a mini torch, or have a goldsmith do it for you. Pickle to remove oxidation.

The gold ring will have a lump where the ends were joined. Grind the outside of the lump off on the 240 lap wheel. (Fig. 7). Fit the gold ring into the inlay hole. Adjust the gold with the forming pliers and grind the hole walls with the No. 4 burr as needed until there is a nice, tight fit.

Mark the host stone with the aluminum pencil where the joint belongs, and angle-grind a bit off the bottom of the gold ring. This will remind you which way the ring goes in, and which way is down. Very important things to know.

Epoxy the gold ring into the inlay hole. I use a two-ton, delayed set, two-stage clear epoxy from Home Depot. Leave the top of the gold ring at or slightly above the host stone level.

On the 240 lap wheel, grind the gold down to the host level, always working toward the center of the hole: (Fig. 8). Grinding toward the inlay hole leaves a crisper inlay margin between the host stone and gold.

Remove hardened epoxy from the inlay hole and at the same time grind off the remaining gold solder and burr from inside the gold ring with a high-speed metal reamer. This is a carbide, not a diamond tool. (Photo 1, bottom right).

Using the Xacto knife, remove the fine strand of gold left around the inside rim from the last step. (Photo 4).

The inlay process is next. Select and cut an opal (or other inlay material), to approximately 1/8" thickness. Orient the opal so it flashes best with the pendant (or earring) held vertically. Mark the top, then start cutting the opal on the 240 lap wheel to fit the hole. Work slowly bit by bit, counter-clock wise around the inlay hole: (Fig. 9). Grind each small section to fit near perfectly before moving on. While cutting the inlay, taper the sides toward the bottom slightly. This allows the inlay to fit tighter into the gold ring as it settles in.

When the inlay fits perfectly (or very nearly), stop working on it!! There is now a choice to be made between finishing the piece as a 'flush' or a 'cushion-mount' inlay. If the opal barely protrudes above the level of the host, a flush-mount inlay is it. In that case, clean the inlay hole and the opal with steam or acetone, mix the epoxy, fill the hole with epoxy, and insert the opal. Squeeze out any air bubbles, as compressed air acts like a spring. When the epoxy sets, grind the opal down to the host level on the 240 wheel, pre-polish the front and rear of the piece as you would an ordinary cabachon, and polish with optical cerium or tin oxide. For opal, the final lap wheel should be a 3,000 rather than the stock 14,000, which burns opal badly. Diamond Pacific's current lap sets have a 3,000 wheel. Earlier models will need one.

If on the other hand the opal protrudes above the host by 1/16" or more, consider completing the piece as a 'cushion mount inlay'. This involves a few extra steps, but adds a third dimension to the piece and allows the opal to flash in more directions. It also retains the opal's intrinsic value, which is lost with a flush mount inlay. This is because the opal may later be removed and used in a different setting.

To make a cushion mount inlay: insert the opal firmly into the hole, sharpen the aluminum pencil, and scribe a fine line on the side of the opal where it meets the inlaid gold ring. (Fig. 10)

Remove the opal and dop it onto a stick (Fig. 11), contour cut down to the scribed line, pre-polish, and polish as with any cabachon: (Photo 5).

Pre-polish and final polish the host and the opal separately in the same manner. Clean the inlay hole and the opal with steam or acetone, and epoxy the opal in. Clean well with acetone before the epoxy sets. When the epoxy has set, scrape off excess with the Xacto knife. Taper the edges of the 'hanging hole'. (Figure No. 12)

For a final professional touch, polish the inside of the hole using 1 1/4" pieces of bamboo skewers with diamond compounds of 325, 600, and then 1200 grit, cleaning thouroughly between each grit with soap, water, tooth brush, and Q-tips. Use a different peice of bamboo for each diamond grit to avoid contamination.

Clean the piece with soap, water, and a tooth brush; and finally window cleaner. You're done. Congratulations!

We recently counted the steps involved, and they came to a grand total of 42! To stay with it all the way takes a level of dedication not many have shown. This guide should help avoid most of my early mistakes. Getting stuck is inevitable. When (not if) that happens, call and we'll try to help. The Lasco catalogue numbers for the burrs are:

• No. 1 - BW6 80 Grit
• No. 2 - BW4 100 Grit
• No. 3 - W1 150 Grit
• No. 4 - CL44 200 Grit

Lasco will provide a complete set of the needed burrs, including core drill, metal and bead reamer. I suggest buying several sets, as they are not expensive, and do eventually wear out. It is frustrating to wait for a shipment in the middle of a project. The set is called 'Opal Inlay Kit'.

The contact info for Lasco:
Lasco Diamond Products
P.O. Box 4657, Chatsworth, California 91313
Phone: (810) 882-2423 | Fax: (818) 882-3550 | Toll Free: (800) 621-4726 | In California: (800) 621-4727
Web: http://www.lascodiamond.com | Email: infor@lascodiamond.com

Your ultrasonic drill may be obtained from Bill Ritter of Cutting Edge Solutions.
Contact info:
Cutting Edge Solutions
22704 Ventura Blvd #336, Woodland Hills, CA 91364
Phone: (818) 992-1982 | Fax: (818) 992-3488
Email: ba.ritter@ earthlink.net :: www.cesdiamondtools.com

We have a website where this article, examples of the work, and our current inventory will be posted, together with prices and other helpful information. The inventory may be seen and the process discussed with the artists at several shows each year. The shows include McDermitt, Nevada (September); Big Sur, California (October); Quartzsite, Arizona (Pow Wow, January); and Tucson (Executive Inn Gem, Mineral & Fossil show (February). We manage at the Tucson Show, and will be set up in the dining room. The jewelry website is www.inaflashopalinlay.com, and the show website is www.eigmfs.com.

Personal contact info is: Tony Thurber
P.O. Box 651551, Salt Lake City, Utah 84165
Phone: (801) 399-1110 | Cell: (801) 792-6027 | Fax: (801) 621-2631
Email: tthurber@q.com

Eric Thurber
Phone: (801) 359-1499, Cell: (801) 865-6496
Email: ethurber@q.com
On the web: www.inaflashopalinlay.com | www.eigmfs.com