{"product_id":"gem-cutting-9780442276300","title":"Gem Cutting","description":"\u003cp\u003eThe term gemcutting is used to describe the process of shaping and polishing faceted gemstones. The artisan undertaking the cutting can also be called a lapidary. While the gemstone in the rough state may be trimmed to remove undesirable material or to separate it on a cleavage line with a diamond bladed saw  accurately described as cutting and once done by the use of a chisel or similar tool to simply break off pieces that were usable as single gemstones. The actual shaping and polishing of a gemstone is a grinding or sanding process. This grinding and sanding is done using a lap  a precision metal plate embedded with grit similar to the more familiar embedding of grit on paper the lap is of high precision particularly for flatness and turned by a motor. (See faceting equipment) The grit material is normally diamond and sometimes corundum for their hardness. Only diamond is hard enough on the Mohs scale to shape and polish a diamond. The initial shaping and facet placement may be done using laps with the more familiar grits of 220  600  1200. The polishing step  however  requires grits that are less familiar 8 000 14 000 50 000 and even 100 000. This grit is also embedded into a metal lap  but sometimes applied manually to the lap during polishing.\u003c\/p\u003e","brand":"My Store","offers":[{"title":"Default Title","offer_id":45921812152373,"sku":"ByrdShop_0442276303","price":238.96,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0627\/8139\/0901\/files\/9780442276300.jpg?v=1787604549","url":"https:\/\/atxbooks.com\/products\/gem-cutting-9780442276300","provider":"ATX Books","version":"1.0","type":"link"}