I am studying faceting and I am wondering how to cut calibrated size gems out of rough to get exact accuracy?
You may want to look at the templates that are offered for sale on sites like ebay and otherwise, generally made of good quality aluminum; and various sizes and shapes available. This might be a starting point. Here are some for Lapidary Templates mainly for Cabs. https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR0.TRC0.H0.Xlapidary+templates.TRS0&_nkw=lapidary+templates&_sacat=0 - and some for Gemstone Templates. For making other types. https://www.ebay.com/sch/i.html?_osacat=0&_odkw=gemstone+size+templates&_from=R40&_from=R40&_trksid=p2334524.m570.l1313.TR0.TRC0.H0.Xgemstone+templates.TRS0&_nkw=gemstone+templates&_sacat=0
Hope that helps. You may need to draw the design on the rough with something like a black pen to get the exact dimensions and then go from there when cutting it.