Quantcast
  Due to a new server, slow response may occur for which we apologize Portal logo
Login/Register
Bactrian Gold Treasure from Afghanistan, coming soon....
/gemstones/feuchtwanger-treatise-stones/page_161 - 2
 

Ch. 5: Gem History Properties

Ch. 5: Gem History Properties Page of 515 Ch. 5: Gem History Properties Text size:minus plus Restore normal size   Mail page  Print this page
FORMS OP THE DIAMOND.
161
hand, if the gems are too thin, their beauty, elements, and general value are likewise diminished. There is a definite proportion of thickness to the breadth of colorless or limpid gems, whereas the cut of the colored gems depends upon the intensity of the color.
FORMS OF THE DIAMOND.
Diamonds were formerly cut according.to their natural fonn, and mostly in the planes of the octahedron. They were called then point diamonds (pierres de nature, or-pointes ingenues).
The following forms aro now, more or less, adopted by the Dutch and English diamond-cutters:
A. The Brilliant. This cut displays to greatest advan­tage the lustre of the diamond : it may be considered as obtained by two truncated pyramids, united together by one common base, the upper pyramid being much more deeolv truncated than the lower. It is formed —a, of the crown, or that part of the stone which remains visible after the stone is mounted ; b, the collet, or lower part ; c, the girdle, or the common base for the crown and eollet ; d, the table, the plane which is formed by the truncature of the upper pyramid ; e, the bisel, that space which lies between the girdle and table ; and f, the collet-side, the space between the girdle and collet. The English lapidaries cut the girdle sharp, where­as the Dutch leave it broad : the crown amounts to one third, and the collet to two thirds of the whole height of the diamond ; the table amounts to four- ninths of the diameter of the brilliant, whereas the eollet only needs one fifth of the (size of the table. The table and collet are regular octagons, and the facets occupied by the bisel are
Ch. 5: Gem History Properties Page of 515 Ch. 5: Gem History Properties
Table Of Contents bullet Annotate/ Highlight
Feuchtwanger. Treatise on Precious Stones.
Suggested Illustrations
Other Chapters you may find useful
Other Books on this topic
bullet Tag
This Page