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CNN just reported an interesting find in the world of crystals: a huge diamond of the highest quality and color. I immediately thought of Kyv and his cutting of crystals when I read it. I often imagine him hunched over his bench with something like this and think of the experts in today's world who cut precious stones.

http://www.cnn.com/2008/WORLD/africa/09 ... topstories

Funnily enough, diamonds are one of the few gems which can be cut using Kyven's techniques.

The technique is called cleaving, and is used to breack a stone along crystaline cleavage planes (not necesarilly paralel to the crystal faces). The most common stones which show perfect cleavage are flourite (those octohedrons you see in most new-age shops are mostly cleaved), Calcite - Iceland Spar (those rhombs which show double refraction), and Topaz (perpendicular to the main axis of the crystal)

The problem with cleaving, is that while the surfaces seem flat, there are usually annoying steps because the crystal cleaves along a plane, but at several layers. It is also almost impossible to polish flat along a cleavage plane due to these weaknesses.

Cleaving of diamonds was used in the medieval period to shape the stone into a more perfect octohedron, and was later used to braeck large mis-shapen stones into smaller ones more suitable for cutting. It is said the when Joseph Asscher cleaved the Cullinan, he fainted because of the stress.

http://www.diamonds-are-forever.org.uk/ ... iamond.htm

Fancy cuts like the scisors cut mentioned in one of the early chapters are impossible by cleaving on natural stones. (I havent said anything because the "crystals" in the story are clearly unnatural stones.)

Modern cutting techniques involve grinding the stone with different grades of grit (usualy synthetic diamond) on a flat wheel, with a stepped stone holder so that the different facets are regular.

I'm no expert cutter, but I have cut several stones, including sapphires, garnets, rock crystal and aquamarine.

Mad Monk wrote:The most common stones which show perfect cleavage are flourite

Ah, yes, perfect cleavage - a topic near and dear to my heart.

Mad Monk wrote:The problem with cleaving, is that while the surfaces seem flat, there are usually annoying steps because the crystal cleaves along a plane, but at several layers. It is also almost impossible to polish flat along a cleavage plane due to these weaknesses.

Fancy cuts like the scisors cut mentioned in one of the early chapters are impossible by cleaving on natural stones. (I havent said anything because the "crystals" in the story are clearly unnatural stones.)

I have wondered about that as well. When Kyv describes a specific flaw and that he has to be careful to "cut around it" to "focus the energy" correctly, I wonder how he is going to do something like that with hammer and chisel. Another thing that raises an eyebrow is the mention of the "tink, tink" sound. With normal stones, you would want to make one hit, in exactly the right spot, then think about it for a while, whereas the act of several small hits of a chisel feels more like a stone carver working on a bust. (yes, Spec, I said bust.)

-M

miraborn wrote: Another thing that raises an eyebrow is the mention of the "tink, tink" sound. With normal stones, you would want to make one hit, in exactly the right spot, then think about it for a while, whereas the act of several small hits of a chisel feels more like a stone carver working on a bust. (yes, Spec, I said bust.)

-M

If you are working in a controlled manner, you do not want to hit too hard. The "tink, tink" sound could be from several lighter taps until that particular chip has come free.

I agree that the process generally as described is more like that of sculptors than gem cutters - BTW before anyone mentions gem carving - that is done by grinding with a wheel. A well cut stone can sometimes take an internal "flaw" or feature like an inclusion and make something spectacular.

For those interested, the International Gem Society has a good overview of Gem Cutting here: http://www.gemsociety.org/info/igem3.htm