The hobby of collecting and polishing of the stones has a magical aspect: What starts out as a rough stone ends up being become a beautiful shining stone such as a diamond, sapphire or opal.
The key ingredient in this process is a product called a "polishing drum" (or rock tumbling). The drum contains one or two containers of stones, abrasive grains and water. As the drums rotate on the base, the abrasive grains slowly wear and polish the outer layer of the rocks.
Among the different kits available, we propose you our 2 favorite modelsas well as a new model ideal for beginners.
Professional Stone Polishing Kit
National geographic stone polishing kit
National geographic gemstone polishing kit
What is a stone polishing kit?
Many people like to collect the interesting stones they find during hikes, trips or other outdoor activities. However, these rough, unpolished stones do not have the luster or visual appeal of a polished gemstone. To achieve this look, you can wait a few thousand years for nature to do its job, or invest in a stone polishing machine, called a "polishing drum".
Polishing barrels are typically sold in one of two configurations: rotary or vibrating. A rotary model rotates a barrel filled with rough stones, abrasive grit and water. As the stones fall, they collide with each other and the abrasive grit. A vibratory model shakes the barrel without rotating it. This technique is faster than rotating, but it does not smooth the edges of the stones as well as a rotating machine.
Many stone polishing kits include a sample bag of unpolished gemstones and other rocks, but you can also use your own found rocks. Some types of rock - mainly those with porous or granular surfaces - are not well suited to the use of a barrel, but those with a hard, non-porous surface can give excellent results.
The process of polishing the rocks can take a month or more, and the contents of the barrel must be thoroughly cleaned as the quality of the grain changes. This process can also be very noisy, as the barrels need to be running 24 hours a day to get the best results. This means you need a location far enough away to reduce noise, while still having an electrical power source.
Rock drum bases and barrels can be sold individually, but there are also complete kits for a younger audience or casual hobbyists. Prices start at €50 for a basic kit, and €300 or more for professional quality drums for gemstone polishing.
Some high-end kits will also allow you to polishing crystals and gems such as: amethyst, tourmaline and topaz.
How to choose the best rock polishing kits?
Here are some of the things to consider when choose the best rock polishing kits :
Type of stone polishing drum
The two types of rock drums are the rotating and vibrating drums. Rotary drums are the most common type of drum used in the rock shaping and polishing process. The drum containing the stones, abrasive grains and water rotates, mimicking the way stones, sand and water collide in rivers and oceans. This process can take weeks.
Although a rotating barrel can also polish the rocks in the final stage, a vibrating barrel is faster and the better option. The vibrator motor vibrates the base of the barrel underneath the drum, which contains the rocks, water and abrasive grit. The grinding action causes friction between the rocks and abrasive grains, which allows to clean and polish the stones in 7 to 10 days.
Number of drums
Single barrel stone drums work with only one type of stone (depending on the hardness of the gemstones) at a time, and the process of polishing the stones takes weeks. With multi-drum drums, you can process several batches in different steps and you don't have to wait for the end of the cycle before moving on to the next batch.
Multi-barrel barrels work well for large quantities of stone, but the single barrel is cheaper and sufficient if you are not in a hurry.
Size of the barrel
The size of the barrel, measured in kg, is one of the essential characteristics to take into account.
A 1.5 to 2 kg barrel is the most common size for beginners and children. A 1.5 kg barrel contains 1 kg of rock and a 500g of water and sand.
A 3 to 6 kg barrel is for serious amateurs.
A 10 to 20 kg barrel is a robust machine for commercial use.
The size also determines the size of the stones and the number of stones to be processed at a time. If you put in fewer stones than recommended for the size of the barrel, the stones may crack or break. Too small a barrel limits the size of the stones and the number of stones you can work in a cycle. Polishing can take up to six weeks before you can load the next batch into a single barrel.
Size of the stones
The maximum size of the stones should not exceed one third of the diameter of the barrel.
A load should contain rocks of different sizes for optimum effect. For example, the largest rock in a 10 cm diameter barrel should be no larger than 2.5 cm. In a 1.5 kg barrel, 50 % of the barrel should be made up of stones less than 1.5 cm in diameter, and 25 % of stones 1.5 to 4 cm in diameter.
Material of the barrel
Plastic and rubber are the most common materials for polishing drums. Inexpensive drums are made of plastic, high-end drums are made of durable rubber, and commercial drums are made of metal with a rubber coating.
The cushioned surface of a rubber barrel protects the stones from damage and rolls the stones better than a plastic barrel.
Polishing drums can be very noisy. Rubber barrels have better noise reduction capabilities than plastic barrels; some electric motors run quieter than others. Stone drums run continuously, 24 hours a day, for weeks on end; they can become noisy.
If you cannot use the stone drum in an isolated area such as a basement or garage, Choose stone polishing kits rated "quiet operation".
Workspace and access
You need space to place the drum and available work space to replace the barrels and change the grain. You also need to have access to a power source to operate the motor.
What are the benefits of purchasing a complete stone polishing kit?
A complete rock polishing kit contains everything you need for the four-step process, right from the start. If you're a beginner, it's a good idea to have your supplies on hand when you read the instructions.
The stone polishing kits include bags of all four types of grit. CSome include enough material for several polishing operations. With a rock polishing kit, you don't have to worry about which rocks to polish together, as all instructions are provided. They come with a variety of rough rocks and a list of the Mohs scale.
Hard gems and precious stones take longer to polish, so it is best not to mix them with soft rocks. Most rocks that are good for polishing have a Mohs scale of 7 and can be bent together.
You can stop the process at any time if your rocks have reached the desired result, but to achieve the high degree of polish, you must follow the four steps, each step taking about a week.
What is usually included in a stone polishing machine kit?
Your stone drum has a metal frame with an electric motor inside. It has a rubber or rubber-lined metal barrel. Plastic barrels are also used for small drums, but they tend to be louder than metal barrels. The size of the barrel determines the weight of the stones that you can drop in one go.
The contents of stone polishing kits vary, but most kits contain abrasive grit, a granular material similar to sand. The grit is labeled coarse, medium and fine for the four steps above. Some kits contain enough of these four types of grit for several polishing processes, while others contain enough for only one.
You can always buy the four types of grain separately.
The kits also contain crushed rock with some quality stones, final polishing grit, a strainer and an illustrated instruction booklet. Drums designed for polishing jewelry-grade stones usually include jewelry accessories such as jewelry attachments like a necklace, two clip-on earrings, a ring and a key ring.
You can also create pendants, cabochons and many other jewelry items yourself.