Every special stone like gemstones, semi-precious stones, cristals, minerals (aso.) needs to be burnished to be given a pretty shape and a cristal shiny surface.
First the raw stone can be cutted with a saw while using a cooling system. For burnishing – some grinding powder out of aluminium oxide must be strewed on a thick glass plate, beginning with the roughest powder, and be mixed with some distilled water, to avoid effecting and breathing in fine dust. The stone must be moved on the mixture in a circular motion until it has a flat surface. This work needs to be repeated with finer grinding powders after cleaning the glass plate and the stone. The finer the powder in use, the stone showes a more glossy surface with more exact colour lines. After a thoroughly cleaning the stone gets polished further on. As underlay for that workstep leather, cotton fabric a wood plate or corkboard can be used. Wich polishing agent should be chosen depends on the stone type. For example aluminium oxid, ceroxide, iron oxide, carbon silicide and diamand paste can be the right polishing agent. The procedure is the same as in the burnishing process. To proof the result: A good polished surface forms waterperls while pooring water on it. In the end the stone must be cleaned really exhaustive.
A children’s workshop with the same working process is for example offered by the “Haus der Entdecker” in Reinsdorf, Germany. In this workshop young kids burnish semi-precious stones leaded by a professional mineral polisher.
Also the “Bernsteinmuseum St. Peter Ording” offers similar workshops for children to burnish amber. After a half hour lesson about amber (about where and how it can be found, what it is and how to work on it) the kids have one hour time to form their own piece of amber. For burnishing they use sandpaper and water and for polishing toothpaste. The amber pieces are prepared with a small whole, so that the children after their work can wear it on a leather tape as necklace.