Technique
Gems were mostly cut by using abrasive powder from harder stones in conjunction with a hand-drill, probably often set in a lathe. Emery has been mined for abrasive powder on Naxos since antiquity. Some early types of seal were cut by hand, rather than a drill, which does not allow fine detail. There is no evidence that magnifying lenses were used by gem cutters in antiquity. A medieval guide to gem-carving techniques survives from Theophilus Presbyter. Byzantine cutters used a flat-edged wheel on a drill for intaglio work, while Carolingian ones used round-tipped drills; it is unclear where they learnt this technique from. In intaglio gems at least, the recessed cut surface is usually very well preserved, and microscopic examination is revealing of the technique used. The colour of several gemstones can be enhanced by a number of artificial methods, using heat, sugar and dyes. Many of these can be shown to have been used since antiquity - since the 7th millennium BC in the case of heating.
Read more about this topic: Engraved Gem
Famous quotes containing the word technique:
“Every notable advance in technique or organization has to be paid for, and in most cases the debit is more or less equivalent to the credit. Except of course when it’s more than equivalent, as it has been with universal education, for example, or wireless, or these damned aeroplanes. In which case, of course, your progress is a step backwards and downwards.”
—Aldous Huxley (1894–1963)
“The audience is the most revered member of the theater. Without an audience there is no theater. Every technique learned by the actor, every curtain, every flat on the stage, every careful analysis by the director, every coordinated scene, is for the enjoyment of the audience. They are our guests, our evaluators, and the last spoke in the wheel which can then begin to roll. They make the performance meaningful.”
—Viola Spolin (b. 1911)
“I cannot think that espionage can be recommended as a technique for building an impressive civilisation. It’s a lout’s game.”
—Rebecca West (1892–1983)