light off-color light yellow COLOR-GRADING SYSTEM Dictionary
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Friday, 21 September 2007

light off-color. A color-grading term used at the mines for a color better than off-color but inferior to second bye.

light yellow. A trade term used by some dealers to cover a wide range of colors in the low end of the dia­mond color-grading scale. Stones in this broad classification show a very obvious yellow tint to the unaided eye. For an approximate comparison of this grade to those used in the color-grading system of the Gem­ological Institute of America and the American Gem Society, refer to chart in Appendix entitled, Com­parison of Different diamond Color-Grading Systems. See also cia

COLOR-GRADING SYSTEM, ACS COLOR-GRADING SYSTEM, COLOR GRADE, CAPE, CAPE STONE, VERY LIGHT YELLOW, yellow diamond, SLIGHTLY YELLOW.

limonite. One of the alteration min­erals found in the kimberlite of the South African diamond mines. A yellowish-brown hydrous oxide of iron.

limpid (or limpidity). A diamond is said to be limpid if it is without body color and very transparent.

Linde Simulated Diamonds. Trade name for man-made yttrium alumi­num garnet (YAG)

1. Linobate. Trade name for man-made lithium niobate. See lithium niobate. Lisa Blue diamond. Originally de­scribed as a soft sky-blue-colored brilliant weighing 37.21 carats. At one time it was believed set in one of the crowns of the Emperor Char­lemagne. It was later recut to 37.05


Dictionary

carats and reported to be flawless and of a rare fancy blue color. This diamond set in a clip was sold in 1961 by Harry Winston in Canada. In 1967 he repurchased the diamond and subsequently resold it in Europe. Lisbon cut. A rarely used modifica­tion of the old-mine cut with an ad­ditional 16 facets.

Lisbon cut

lithium niobate. Relatively rare col­orless to colored man-made dia­mond simulant. Its hardness is about 6, S.G. = 4.64, R.I. = 2.21-2.30, and has a high dispersion of 0.120 for the Fraunhofer B-G lines. Manufactured by the Czochralski pulling method