| 释义 |
‖ naat, n. Diamond Industry.|nɑːt|
[Afrikaans naat seam, suture, f. Du. naad.]
An irregularity in the structure of a diamond, caused by a change of direction in the grain; a ‘knot’ or blemish. Also, a diamond having such a feature.
1945Industrial Diamond Rev. Sept. 205/2 Knot, Naat (Min.), irregularity of crystal structure in a single crystal diamond. Because the cleavage planes cannot easily be found, it is generally believed that such stones have a greater resistance to abrasion. 1962S. Tolansky Hist. & Use of Diamond ix. 147 If changes in grain direction are encountered on a crystal (naat is the word for such a change), the impregnated wheel can readily cope. 1970E. Bruton Diamonds xi. 190 The sawyer..has..to watch for any changes of hardness through an area of different crystallization. These naats sometimes have rope formation or spider's web formation in a stone and will turn the blade and spoil the cut. 1984G. Davies Diamond ix. 228 The blade..will find it very difficult to make any progress if it comes up against a piece of the diamond which has a different crystallographic orientation. These mis-oriented pieces, the ‘naats’, are analogous to knots in a piece of wood. |