Jewelry Lovers

Jewelry from polished or even unpolished rocks and pebbles is probably the oldest and most fascinating of all the crafts — and your involvement can be as simple or as extensive as you like, and almost as cheap or as costly as you decide.

You can go out and collect stones yourself or buy them at a shop; you can polish pebbles until they have a permanent shine, or you can buy them ready polished. You can make up polished stones into jewelry, using your own base or bought settings which can be cheap gilt ones or expensive settings in silver or gold. The joy of the craft comes from the beauty of the stones themselves — and the part you can play in bringing this out.

Equipment

The best way of polishing pebbles is to use a tumbling machine. These are not expensive and can be purchased from a good crafts shop. For the beginner, however, there are tumbling kits which include all the necessary equipment for polishing the pebbles you have already collected. Apart from the tumbling machine, they include the necessary grits and polishing agents, epoxy resin glue, a selection of findings or jewelry mounts to which you attach your polished stones and even a batch of stones for polishing.

Polishing pebbles

A tumbling machine consists of a small barrel and two parallel rollers. These are turned by pulleys, and a rubber belt, driven by an electric motor.

First, place the pebbles in the barrel and fill it with water. Add one tablespoon of coarse silicon carbide grit (80 grade) to the water and secure the lid firmly to the barrel, which is then placed onto the rollers. The barrel is then turned on the rollers, at a speed of approximately one revolution per second, for the next seven days. While this process is going on the pebbles will roll, or ‘tumble’, against each other as the barrel turns, and the silicon carbide grit will gradually wear away all surface roughness.

When the first stage is completed, remove the barrel from the rollers and wash the pebbles thoroughly in fresh water to remove all traces of the coarse silicon carbide.

The barrel will contain quite a lot of sludge at this stage. Do not pour this down the sink or you will run the risk of blocking the plumbing. Simply empty into a plastic bag and throw it away. Rinse the barrel thoroughly to make sure that all traces of grit have been removed. Put the pebbles back into the barrel and fill up with clean water once more. Having done this, add one tablespoonful of medium silicon carbite grit (220 grade) to the water, and repeat the tumbling process for a further seven days. During this second stage, surface scratches caused by the coarse silicon carbide are removed from the pebbles. At the end of the second seven day period you should remove the pebbles from the barrel and wash them carefully under running water. You should now clean the barrel thoroughly once more. Now, the entire process should be repeated for a third time — this time using fine silicon carbide (440 grade). This will give a smooth matt finish to each pebble.

After three weeks of continuous rotation inside the barrel, the pebbles should be absolutely smooth and ready to take their final polish. However, you must first remove all traces of silicon carbide on the pebbles and from the inside of the barrel or you will fail to achieve a high polish during the final stage. Place the pebbles back in the barrel, fill it up with clean water and add one teaspoonful of tin oxide or cerium oxide. Allow the pebbles to tumble inside the barrel for approximately twenty four hours. After this has been done, the pebbles will be polished to a brilliance which will enhance their natural colours and beauty. You should now give the pebbles a final rinse under running water.

Rules for polishing

The two main points to remember for successful polishing are:

1. Always load the barrel with pebbles of a similar hardness. It is easy to carry out a ‘hardness test’ when collecting your pebbles. Take a small penknife with you when searching a beach for likely specimens. As you pick up each pebble, scratch its surface with the blade of the knife. Put all those which cannot be scratched by the knife into one bag, and those which are easily scratched into another.
2. Include as wide a variety of pebble sizes as possible when filling the barrel. You should never load your machine with pebbles of a uniform size.

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Pebble polishing techniques