Tumblestones
76 Mix - Cape Town, South Africa
South Africa is often considered the "gemstone capital of the world" as almost half of the world's gemstones are found there, that is why we import our Tumblestones directly from Topstones, Cape Town, South Africa. Topstones is the largest tumble-polishing factory in the world and processes some 150 varieties of stone from all around the world. Prime sources of gemstone-material include Southern Africa, Brazil, Madagascar,Mozambique, Siberia and Alaska.
Our mix contains only natural stones (not dyed stones) the photo above is an example of the actual stones we have in stock. All purchases are sent direct from our family run shop Tumbletopia World of Stones in Barnstaple, North Devon.
A stunning multicoloured mix of over 76 different gemstones. There are a wide variety of tumbled polished gemstones in the mix, many popular Southern African stones such as Tiger's Eye, Rose Quartz, Amethyst, Jasper, Blue Lace Agate, Crystals and Agates. If you are lucky, you find virtually anything including Lapis Lazuli, Garnet and other really exotic stones.
Sizing and Grading
Tumbled Gemstone Sizes. This chart shows the actual sizes of the stones we offer (1 grid square = 1cm).
We also include the approximate amount of stones per kg. There will be some variation due to stone shapes and specific gravity, but these figures have proved to be accurate averages over many years of production.
Tumbled Gemstone Gradings.
Sorted Grade: Tumblestones orders of 400g or less from size 1LG upwards are hand sorted. Initially, obviously off-coloured or mixed materials are removed. The batch is then inspected for chipped or broken stones. These are removed and what remains constitutes SORTED GRADE stock.
Unsorted Grade: It is difficult to hand sort sizes 00, 0 and 1SM economically, therefore these sizes are generally sold UNSORTED. The high percentage of usable material and the lower price combine to make UNSORTED GRADE stones most acceptable.
This chart shows the sizes in which our stones are offered, together with the average number of stones per kilogram in each of our different sizes. There may be minor variations due to individual stone shapes, differing specific gravity and other inherent factors, but the yields quoted have proved to be an accurate average over many years of production.
A tumbled-polished gemstone is one that has been smoothed and polished to a high gloss by slowly grinding the stones against each other in barrel-like tumblers. Depending on the stone type, and the skill of the person managing the process, it may take anything from a few days to several weeks to achieve the desired result.
Although the tumbling process remains a fairly "mechanical" process, there is a great deal of skill involved in obtaining the desired "polish" to the different stone types. However the basic process is one of using a grinding paste of Silicon Carbide Abrasive Powder and water to grind the stones to shape followed by a final tumbling with a polishing powder.
What is a Tumblestone?
Gemstone tumbling was started commercially in the United States in 1953. At that time, the tumblers used were literally no more than household paint cans, but as demand for the fabulous gemstone-products increased, the tumbler sizes increased until they reached the "6000-pound" tumblers which proved to be an ideal mix of size and efficacy. This size of commercial tumbler is still used today. The vibrating tumbler then entered the market as it speeded up the process of tumbling certain gemstone types and sizes. Although the tumbling process remains a fairly “mechanical” process, there is a great deal of skill involved in obtaining the desired “polish” to any stone type – and a variety of materials (other stones, gravels, sand, sawdust, iron-filings, etc) might be added to the tumbler at various times to buff the stone.
