Natural Crystals
Many jewelry designers choose to avoid traditionally cut gemstones, instead using natural forms that require minimal cutting. Gemstone crystal clusters, slices and pebbles can all be transformed into precious gems simply by trimming the overall shape, grinding the base flat or polishing a surface.
Crystalline drusy surfaces from the linings of agate geodes, grape¬like botryoidal crusts and pyrite layers will give a design brilliance, sparkle and texture. Fossilized coral and wood can provide decorative abstract patterns, while opalized wood and shell or baroque pearls can add structure and form to a unique piece of jewelry. Crystal shapes from a range of materials can be used in jewelry — try aquamarine, heliodor, tourmaline, quartz or diamond.
Usage and common problems
Some natural crystal forms are collectables or mineral specimens, which can make them more expensive. This is the case with perfect, fully terminated crystals, material with unusual inclusions or colour banding, and some crystal formations. Any diamond, tourmaline or beryl crystals that might be used for faceted stones will have a higher price. Polished crystal slices can be found in many materials. Tourmaline is wonderful for its bi- or tricoloured cross-sections, but has become quite expensive. Quartz can be sliced to display interesting inclusions of hematite leaflets, rutile and tourmaline needles and iron or manganese staining, as well as colour zoning. Beryl has a suitable crystal shape for slicing, although emerald is a little too fragile (and expensive). Sliced agate can provide beautiful coloured banding and dendritic inclusions, and is a good value.
Choosing a Crystal for faceting os setting
The outer edge of the crystal should be undamaged, otherwise it might break when you are burnishing the surrounding wall. Drusy and botryoldal crusts are slightly fragile and need to be treated with care. Ideally, they should have a flat base and slightly beveled sides so they can be given a protective setting that is flush with the surface. Check for cracks and avoid pieces of drusy that have very thin areas.
Drilling can be problematic with certain crystal forms, so take advice first. A hand drill or power rotary tool with flex-shaft attachments may be used. A high-speed twist drill bit will make holes in softer stones, such as shell, amber, malachite, marble, sugilite and lapis. For material with a hardness between 5 and 7 Mohs you will need to use tungsten carbide drill bits with embedded diamond grit. Diamond needle files or diamond -impregnated burrs will allow you to shape material and tidy up the crystal ends. Cool the gemstone with water to prevent it getting too hot and becoming damaged.
Natural crystal forms require special settings. Flat slabs or slices of crystal can be held with walls of burnished soft gold or silver, to allow light to travel through the piece. Work gently with the burnisher to avoid overstressing the slices, as thinner material or material with a large surface area will be vulnerable to pressure. Small individual crystals can be capped, wire wrapped, caged or drilled as a briolette. Drilling a diamond crystal requires specialist equipment; ask a diamond cutter for help.
If you are interested in learning stone cutting or shaping, many cities have a local lapidary club with experts that can show you both the basics, and the finer points of stone cutting and shaping.
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