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Bureau of Mines / Minerals yearbook: Metals and minerals 1978-79
Year 1978-79, Volume 1 (1978-1979)

Baskin, G. David
Gem stones,   pp. 363-375 ff. PDF (1.3 MB)


Page 365

 
Carat 
weight 
Description, 
color' 
Clarity2 
(GIA terms) 
Price range 
per carat 
Median price per carat 
Early 
December 1979 
December 1978~ 
0.04-0.08               
G-I 
VS1 
$450- $755 
$587 
$611 
.04- .08               
G-I 
Si1 
385- 615 
540 
546 
.09- .16               
G-I 
VS1 
475- 872 
640 
731 
.09- .16               
G-I 
Si1 
425- 695 
595 
643 
.17- .22               
G-I 
VS1 
740- 1,495 
980 
945 
.17- .22               
G-I 
Si1 
675- 1,315 
895 
850 
.23- .28               
.23- .28               
.29- .35               
G-I 
G-I 
G-I 
VS1 Sl~ VS1 
840- 1,745 
700- 1,535 
935- 1,980 
1,220 
1,090 
1,400 
1,115 
982 
1,242 
.29- .35               
G-I 
511 
775- 1,690 
1,120 
1,065 
.46- .~5               
.46- .55               
.69- .79               
.69- .79               
G-I 
G-I 
G-I 
G-I 
VS1 Sl~ VS1 Si1 
1,600- 2,488 
1,250- 2,140 
2,000- 3,185 
1,500- 2,746 
1,950 
1,540 
2,605 
2,103 
1,565 
1,348 
2,035 
1,861 
1.00-1.15               
1.00-1.15               
1.00-1.15               
D 
E 
G 
 FL 
VVS1 VS1 
35,000-38,500 
14,000-19,500 
4,428- 7,500 
37,000 
17,000 
6,100 
22,500 
 NA 
 NA 
1.00-1.15               
H 
VS2 
3,500- 5,700 
4,650 
NA 
1.00-1.15               
I 
511 
2,500- 4,300 
3,170 
NA 
 NA Not available. 
 1Gemological Institute of America color grades: D—colorless; E—rare
white; G-I—traces of color. 
 2Clarity: FL—no blemishes; VVS1—very, very slightly
included;
VSi—very slightly included; VS2—very slightly included,
but more
visible; S11—slightly included. 
 3Adjusted from Keystone price formerly published. 
GEM STONES 
365 
 The retail price of a finest quality, 1-carat diamond tripled between December
1976 and December 1978. This was due in part to devaluation of the U.S. dollar
and the fact that thediamond market became very speculative early in 1978.
In order to dampen speculation in the resale of rough gemquality stones,
De Beers Consolidated Mining, the South African company controlling 85% of
the world's diamonds, imposed a 
40% surcharge on its April sales of rough stones; during May, June, and July,
the surcharge was reduced to 25%, 15%, and 10%, respectively. The surcharge
had the desired effect in that it quelled speculation and suspected hoarding
of rough diamond 
at a time when De Beers' supplies were believed to be limited. Following
the removal of the surcharge, De Beers raised prices an average of 30%. In
September 1979, De Beers' prices again rose an overall 13%; the largest increase
affected cut stones weighing over one-half carat. 
 Emerald prices decreased in 1979 approximately 10% in all but the finest
qualities. An increase in the supply of Zambian stones brought the decline.
 Other precious and semiprecious stones also increased in price and popularity.
Many buyers turned to colored stones as fine diamonds became more expensive.
FOREIGN TRADE 
 The following section contains foreign trade statistics for 1978 and for
1979 (in parentheses). 
 Exports by the United States of all gem materials amounted to $492.7 ($661.0)
million, and reexports to $290.7 ($279.0) million. Diamond accounted for
93% (94%) of the value of exports and 96% (94%) of the reexports. Exports
of diamond totaled 332,199 (213,481) carats valued at $457.1 million ($623.1
million). Of this total, diamond cut but unset, suitable for gem stones not
over 0.5 carat, was 49,057 (59,300) carats valued at $41.7 million ($69.5
million); and cut but unset, over 0.5 carat was 170,316 (145,864) carats
valued at $402.1 million 
($552.5 million). Exports of uncut diamond were 112,826 (8,317) carats valued
at $13.3 million ($1.1 million). 
 Reexports of diamond amounted to 1,266,998 (982,027) carats valued at $279.6
million ($261.5 million), in categories as follows: Rough or uncut, suitable
for gem stones, not classified by weight, 1,179,038 (913,981) carats valued
at $169.1 million ($150.1 million); cut but unset, not over 0.5 carat, 37,742
(42,841) carats valued at $18.8 million ($25.1 million); cut but unset, over
0.5 carat, 50,218 (25,205) carats, valued at 
$91.7 million ($86.3 million). 
 Exports of all other gem materials by the United States amounted to $27.5
million 


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