Thursday, June 14, 2007

The Gilson Opal Triplet And How To Make It

Julius Lippa and Pierre Gilson writes:

The opal triplet is a three piece gemstone made by cementing together a thin piece of precious opal sandwiched between a backing piece and a layer of optical quartz or other hard clear material.

Gilson opal: Gilson 'T' Quality opal is specifically made for triplets. It was created to satisfy the wishes and desires of countless opal lovers for the ideal material.

No matrix: Gilson opal is 100% usable since it is solid opal with no matrix.

Toughness: Gilson opal is tougher, harder and can withstand more heat than most opal. However, as with any fine gem material it deserves to be handled with care.

Material list

Opal: Triplet grade precious opal.

Cap material: Optical quartz, (natural or synthetic), sapphire or hard optical glass.

Base material: Jade, opal potch, agate, jasper, basenite, obsidian, glass or plastic.

Epoxy: Two part epoxy which dries water clear.

Lampblack: Lampblack for backing if needed or desired.

Lapidary equipment: Equipment necessary to make flat surfaces and to finish a cabochon.

Steps to follow

1. Color: Wet opal with clean water to show color pattern.

2. Orient: Orient opal for best color pattern for sawing.

3. Sawing: Use thin saw blade to avoid wasting opal in saw cut. Use a saw vise or a steady rest rather than trying to do this freehand (see # 7 opal thickness)

4. Grinding: Assuming that your saw blade leaves smooth areas on the sawed materials start with # 220 abrasive, then go to # 600 abrasive. It usually is not necessary to go beyond # 600. The perfectionist who continues to finer finishes such as # 1200 or finer (a semi-polish) will then have the brightest triplets.

5. Method: The individual method of grinding flat surfaces depends upon available equipment, personal preferences or techniques such as:

a) Abrasives of various sizes used on a sheet of flat glass. (use entire surface area so low spots do not develop)

b) Wet or dry abrasive paper used on flat surface.

c) Faceting laps. (highly recommended and used by Gilson Labs)

d) Flat-faced diamond discs. (highly recommended and used by Gilson Labs)

6. Cleanliness: Wash hands and material being worked on after each step to avoid contamination.

7. Opal thickness: How thin to grind the opal depends upon personal preference in color. Usually the thinner the opal the darker the color. As a starting point begin at 0.20mm (.008 inch) slices and if you feel it is necessary work the opal thinner until color suits you. (See # 16)

8. Base thickness: Base thickness 1/16 inch (1.6mm) or as desired to fit mounting. Put a 30 to 45 degree angle on base to clear mounting.

9. Cap thickness: Cap thickness can vary from 1/16th inch to ¼ inch (1.6 to 6mm). This is an area where the size of the triplet and personal tastes dictate the answer. The thicker the cap the more the magnification effect, but also the heavier the triplet becomes.

10. Components: The base and cap materials receive similar treatment as the opal to get to a finished surface. The exception would be when caps in their finished state are cemented to the opal and are not formed from an original piece of rough material.

11. Cleanliness: Before cementing any triplet components together we come to a very important subject; Cleanliness which is the secret of a good bond. Clean all surfaces which are glued together with acetone. Let dry, then clean with alcohol.

12. Cleaners: Cleaners cementing leave residue, therefore freshly ground surfaces after step 11 above can be rinsed with clean water and allowed to dry on clean paper or rags without ever again touching the ground surfaces with your fingers or anything else prior to joining together.

13. Heat: Dry opal, cap and base materials at temperatures under 180 degrees Fahrenheit (82 degrees centigrade) in oven, or on top of oven near pilot light or under an electric light bulb. Bring up to drying temperatures gradually ( see # 20)

14. Three parts: When all three parts of the triplet (flat surfaces) have been prepared they then are joined together, two pieces at a time, with a two part epoxy which dries water clear. (see # 19 for use of lampblack)

15. Handling: For ease in handling after one surface of the opal has been finished glue finished surface to backing or cap to grind opal thin enough to get best color (see # 19 for use of lampblack)

16. Checking for color: Wet the opal cemented to cap and place on a shiny black surface such as a piece of glazed tile to judge when color is clear and bright. If color does not suit your tastes, grind thinner until it meets with your approval, alternating between grinding and checking until you are satisfied. Repeat same method of checking and grinding for opal mounted on backing.

17. Assembly: Mix epoxy gently to avoid air bubbles and apply epoxy in thin layer to both surfaces which you join together. These two components should be warm when put together. Put the two pieces together with firm finger pressure and a sliding motion to squeeze out air bubbles and surplus epoxy. Use little clamps, clothes pins, weights, etc. to hold parts together until epoxy sets properly (24 hours).

18. Surfaces: All surfaces which are joined together must be flat, clean, dry and scratch free. Any uneven area between surfaces may capture air and be visible as air bubbles or opaque spots.

19. Lampblack: The use of lampblack in the epoxy gives a bright black shiny surface to the backing material and also permits the use of base materials which are not black originally. The amount of lampblack to use in epoxy is about .5mm in diameter for a 10 x 12 mm stone. It is a trial and error method easily learned after a few trials on test materials.

Note: Using too much lampblack degrades the epoxy resulting in a weak bond and using too little lampblack results in epoxy not being dark enough. Most black materials become sufficiently reflective with use of clear epoxy and addition of lampblack is not needed.

20. Water: Use plenty of water when working with the opal to keep it cool. Do not lean the hard way that overheated opal may crack or craze.

21. Clarity: Everything possible should be done for utmost clarity and a part of this process is to use an epoxy which dries water clear. Any coloring in the epoxy between the cap and the opal will dull the color of the opal.

22. Cap: The cap used over the opal must be flawless and water clear since this domed crystal cover both magnifies and enhances the colors and patterns while at the same time protecting the opal.

23. Color change: Experimentation with various base materials revealed that the red and pink colors in an occasional piece of opal from any source would be greatly improved when backed with a bright red material. In opal which exhibits this phenomena the red and pink colors are already visible. These make up into very pleasant stones when backed with black, however, some people think the red backing produces a great improvement.

24. Base: Almost any strong material can be used which expands and contracts at approximately the same rate as opal. (avoid brittle materials)

25. Durability: Opal like glass is six on the Moh’s scale of hardness. Cementing a quartz cover on top of the opal increases the hardness to seven plus or to nine with a clear sapphire cover.

26. Free forms: Free form triplets with their unique charm are especially adaptable to modern jewelry, lending themselves to great variety of design.

27. Good food: You well may ask how <> gets into an instruction sheet on triplets. It was inserted to remind you that like good food the triplets you make can only be as good as the ingredients used and the skill and craftsmanship of the worker.

28. Black opal: The opal triplet probably was created by an unknown genius to save and use thin bands of precious opal. He little realized that his brain child often leads to confusion between genuine black opal and very good triplets even amongst those in the jewelry trade. This sort of confusion can occur when a thin cap is used and the juncture of cap to opal can not be seen when hidden in a mounting.

29. Magnifying lens: A magnifying lens is a handy item to use when assembling triplets so you can look for air bubbles and if any are objectionable to you then slide the parts apart and wash off with alcohol, dry and try again.

30. Other opal: Precious opal suitable as triplet material from any of the world’s sources may also be processed with these instructions.

31. Lapidary: It is assumed that the reader has mastered the techniques of lapidary. Finishing the triplet is simply the process of making a cabochon.

These are some mistakes people have made and things to avoid:

- Opal slices used so thick that black backing has no effect.

- Despite emphasis on using clear cap examples of window glass with all kinds of inclusions, bubbles, etc., as well as quartz with flaws and yellow discoloration have been used with poor results.

- Opal used in wedge shape so one end of triplet is dull and the other end bright.

- Epoxy mixed on a dirty surface resulting in triplet with a weak bond or visible dirt within.

- Using very old epoxy with the catalyst spoiled so the epoxy will not harden properly.

1 comment:

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