Gems and Gemology, Winter 1948-49
De Beers Consolidated Mines, LTD., have recently supplied the Gemological Institute of America with the following classifications now in use by that company in grading rough diamonds at the Dutoitspan, Wesselton and Bultfontein mines (De Beers and Kimberley closed). Graduates and advanced students of the Institute will notice that the new classifications differ somewhat in terminology from the older classifications contained in the Institute's diamond course. This new classification will now replace the old one in that course.
a) Close Goods.
b) Irregulars and Shapes as in "a" but not necessarily symmetrical or octahedral.
c) Spotted Stones.
d) Cape and Yellow Spotteds as in "c" but of a progressively deepening yellow color.
e) Browns. Stones of a progressively deepening brown color.
f) Greens. Stones of a progressively deepening green color.
g) Melee "a" to "f" in sizes under one carat and larger than "l."
h) Cleavage. Broken pieces of a reasonable thickness, and not "twinned" (Macled or Naated).
i) Chips as in "h" but under one carat in weight.
j) Macles. Twinned crystals of a reasonable thickness.
k) Flats. Thin pieces, whole or broken, including thin macles.
l) Sand. All qualities in a very small size, passing through a .070 inch sieve.
m) Industrials. Diamonds not suitable for cutting, and allocated to industrial uses, including bort, which is only suitable for crushing into diamond powder.
The percentages of each classification as of 1948 was estimated by the Sorting Room of De Beers Consolidated Mines, Ltd., as a comparison.
| Description |
Bultfontein
|
Wesselton
|
Dutoitspan
|
| a) Close Goods |
.40
|
1.91
|
3.44
|
| b) Irregulars and Shapes |
.19
|
.73
|
5.56
|
| c) Spotteds |
15.78
|
6.30
|
8.05
|
| d) Cape and Yellow Spotted |
.43
|
.54
|
9.54
|
| e) Browns |
.50
|
.94
|
2.38
|
| f) Greens |
1.44
|
---
|
1.50
|
| g) Melee |
15.39
|
10.67
|
5.79
|
| h) Cleavage |
6.10
|
6.38
|
17.83
|
| i) Chips |
4.76
|
5.04
|
4.17
|
| j) Macles |
5.25
|
3.71
|
7.39
|
| k) Flats |
5.63
|
11.21
|
9.05
|
| l) Sand |
2.04
|
2.80
|
.82
|
| m) Industrials |
42.09
|
49.77
|
24.48
|
The rare colored stone is described by the Diamond Trading Company as pure and of an original vague heart shape with one concave side. There was some risk that this cavity would not disappear when it was polished to its estimated dimensions, with the result that any recurring would greatly reduce its weight. The diamond was considered of such rarity and beauty that Mr. Briefel determined to polish it to shape and so avoid any risks in sawing or cleaving.
At the "cross-work" stage the pink diamond weighed 38.5 carats and still retained its rare pink color which was constant through the stone. Hopes were raised that the diamond might, when finished, weigh considerably more than the minimum guaranteed by the firm.
The polishing was completed April 14, 1948 and the result Was a perfect brilliant of a deep pink color weighing 23.6 carats. The future of the unique pink diamond is not at present known as Her Royal Highness has not yet decided on the manner in which the stone will be mounted.
TOTAL PRODUCTION OF DIAMONDS
From 1888 to 30th June, 1948
| Mine |
Metric Carats
|
| De Beers Mine |
23,201,719 ¼
|
| Kimberley Mine |
14,624,822
|
| Wesselton Mine |
16,096,230
|
| Bultfontein Mine |
17,412,795 ½
|
| Dutoitspan Mine |
8,831,712 ½
|
|
Total
|
80,167,281 ¼ |
|
Tailings (30th June, 1901 to 30th June, 1915)
|
3,350,111 ¾ |
|
Grand Total
|
83,517,393 |