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Pulp Gems and Precious Metals

Page history last edited by Michael 10 months, 2 weeks ago

 back to Boodle and Swag




   In 1932, rough uncut diamonds imported into the United States were worth an average of $37.68 per carat; cut, but unset diamonds were worth $42.74 per carat.

   Bar silver was worth an average of $0.39 per fine ounce in 1932. The value of a fine ounce of gold was $20.67 up until the United States went off the gold standard in March; exchange value after that point was an average of $28.73 per fine ounce.

-- source:  World Almanac and Book of Facts for 1934


   Bar silver was worth an average of $0.49 per fine ounce in 1933, and $0.48 per fine ounce in 1934. Gold was worth $30.38 per fine ounce in 1933, and $56.71 in 1934.

-- source: World Almanac and Book of Facts for 1936


    "... Deeply colored red, green and blue diamonds, although the most expensive of gems, are not considered here, since they are so rare... [also not obedient to standards of valuation, due to rarity] are red, green, or blue diamonds, white diamonds of unusual size and brilliancy, rubies of over four carats, emeralds of fine deep color and relatively free of flaws, particularly if of good size, and unusually fine sapphires."

   Prices of gems in America have been affected by "... the reduction in July, 1930, of the American duty on cut gems from 20 to 10 per cent ad valorem."

   Good, well-cut one carat emeralds in 1934 are worth about $450; one carat rubies, about $200; and one carat sapphires, about $120.

   "... exceptionally large rubies (3 to 9 carats or more), due to their great rarity, are the most expensive of stones. Such stones bring from $3000 to $7000 a carat." Good, well-cut rubies of two carats are worth about $2500 each.

   "Fine large sapphires are by no means as rare as fine large rubies or emeralds, and in consequence the price increase per carat is by no means as great as in those gems: a ten-carat stone might be worth from 40 to 60 times the value of a one-carat stone."

   Emeralds "... of good quality over one-carat, more or less, increase in value by the square of the weight -- a generalization true since the 16th century." Thus a nine carat emerald might be worth $36,450.

-- source:  A Historical Study of Precious Stone Valuation, by Sidney H. Ball, in Economic Geology, August, 1935


   1934 imports of diamonds into the United States:   rough, uncut 79,695 carats worth $4,261,921; cut but not set, 330,617 carats worth $15,538,902

   "Recovery in the diamond industry, first noted in the summer of 1932, continued at an accelerated rate in 1935, but the industry cannot be prosperous until the United States, its best customer, enjoys good times. The trade, however, is confident of the future, and virtually every index of the industry improved, in comparison with 1934, by 15 to 75 percent."

   "Sales of rough by the Diamond Trading Co. exceeded £6,000,000, a 55-percent increase over those of 1934."

-- source:  Minerals Yearbook 1936


Buying and Selling


     Dealers will pay about 30% of the retail price to a "walk in customer"; they pay about 40% of retail price to established wholesalers. Sales of stolen gems to fences (i.e., buyers aware of their illicit nature) will bring at most 1/6th of the ordinary retail value, down to perhaps 1/10th received by an unlucky seller.




     Diamond prices go up (very roughly) by the square of the carat weight, from 0.5 carats to 6 carats. Above 6 carats, price is entirely individual.  Thus price per carat of diamonds will be:


diamond prices per carat, 1932

carat weight

rough, uncut

cut, unset

under 0.5



0.5 to 0.69



0.7 to 0.89



0.9 to 0.99



1.0 to 1.49



1.5 to 1.99



2.0 to 2.99



3.0 to 3.99



4.0 to 4.99



5.0 to 5.99




     This doesn't consider odd colors or cuts. Keep in mind that  " ... in 1932 worldwide diamond sales [new diamonds, not previously on the market] had been only $100,000." Diamond merchants aren't going to give you a lot of money for your stones between 1928 and ... 1938?

     There are less than 30 red diamonds found before 2018, most less than half a carat, and the largest being 5 carats. Even by 2020, "less than a handful" of red diamonds above 0.2 carats are available on the world market. Blue and yellow diamonds are also very rare. The famous dark blue Hope Diamond, of 45.5 carats, could probably bring $500,000 in a legal sale in the 1920s. In a general sense, a brightly-colored blue diamond will be worth at least five times a "white" diamond of the same size and cut; a red diamond, at least ten times a "white" diamond.

     Shades of less-vivid or less-desirable colors, such as pink, brown and orange, are worth more than "white", but their value is hard to specify.

     South African diamond output for 1934 was 440,312 carats, with a total value of $7,245,458.64, or about $16 per rough uncut carat.




     The first line shows per-carat prices; the following lines are prices for a stone of that size:


ruby prices, 1934

carat weight

rough, uncut

cut, unset

under 0.5 ct

$75 per ct

$100 per ct




















one of Captain Lotta's crew holds a 250 carat ruby, worth more than a million dollars!




     The most valuable gem in the beryl family. The first line shows per-carat prices; the following lines are prices for a stone of that size:


emerald prices, 1934

carat weight

rough, uncut

cut, unset

under 1 ct

$300 per ct

$400 per ct



















     The first line shows per-carat prices; the following lines are prices for a stone of that size. This table is for fine blue sapphires, for which the price increases between 1 and 10 carats by the 1.6th power.


sapphire prices, 1934

carat weight

rough, uncut

cut, unset

under 1 ct

$75 per ct

$100 per ct






















     Prices given are per carat for opals of at least good grade; fine and extra fine grade add 50% or 100% to value. Precious or "noble" opals are rare in larger sizes. There are many varieties (black, crystal, fire, pink, etc.) which can be easily worth $100 per carat; polish and shape also affects prices. Note that opals are fragile gemstones


opal prices, 1934

carat weight



under 1 ct

$0.50 per ct

$2 per ct

1-5 ct

$0.75 per ct

$3 per ct

5-10 ct

$1 per ct

$6 per ct

10-50 ct

$2 per ct

$12 per ct




     Prices given are per carat, for fine quality cut aquamarines. Since aquamarines are available in large sizes, the  price per carat is constant up to at least 50 carats.

     Aquamarines are a blue-green form of beryl; yellow or golden beryls (chrysoberyls) are the other, less-comon variety.


aquamarine prices, 1934

carat weight

rough, uncut

cut, unset

under 1 ct

$5.40 per ct

$7.20 per ct

1-50 ct

$6 per ct

$8 per ct

51-100 ct

$7.50 per ct

$10 per ct




     Prices given are per carat for A grade stones; other grades are AA (worth about 4x more than A grade), AAA (worth about 10x more than A grade), and AAAA grade (worth about 25x more than A grade). The value of turquoise is somewhat subjective.


turquoise prices, 1934

carat weight



under 1 ct

$0.05 per ct

$0.50 per ct

over 1 ct

$0.10 per ct

$1 per ct




     Cultured pearls from Japan first appeared on the market in 1921; they can't be told apart from natural pearls (without cutting them in half), and have driven the price of natural pearls down by 98% from their peak before 1920 (along with the effects of the Great Depression, and the growing use of plastics for buttons). In 1930 there was a "pearl crash"; prices on the London market dropped 85% in a single day, and continued to decline through the 1930s. Attempts by various nations to forbid marketing cultured pearls with the name "pearl" failed.

     A two-strand necklace of 128 matched pearls was worth $1 million in 1917; the same necklace might be worth $22,000 in 1933, and was still only worth $157,000 in 1957. A strand of 99 matched pearls (4 carats each, about 8.5 mm) worth £75,000 in the early 1920s is worth only £1,650 by 1934. 

     Since at least the early 17th Century pearl prices in Europe increased by the square of the weight (see Gemmarun et Lapidum Historia by Anselmus Boethius de Boodt, pub. 1609).

     Colored pearls, from the South Seas, have been available in trade since the mid-19th Century. So-called "baroque" pearls (with odd shapes) can be valuable (most are not --  it's difficult to find attractive and matched sizes and shapes, worth only 13 cents per carat); they can be quite large, however (up to 50 carats). The largest pearl ever found was the "Pearl of Allah", a very baroque shape indeed, weighing 14 pounds, brought up in 1934 in the Philippines. Circa 1940 this pearl was placed on display at Ripley's Museum in New York City, with a claimed value of $3,500,000.

     In 1958, the largest round pearl with a good lustre and color found in the pearl fisheries around India was of 7 carats; the next biggest that year was 6 carats. Huge historical pearls, noted in chronicles, are up to 30 carats in size. The general categories of natural pearls on the market are "seed" (individually small -- under 2mm size -- but about half the production by weight), "baroque" (odd shaped), "round" (the ordinary type), and "first" (the best type and color, etc.).


pearl prices, 1934

carat weight

diameter, mm


< 0.1 ct

 < 2 mm

< $ 0.05

~ 1 ct

5 mm


1.6 ct

6 mm


2.7 ct

7 mm


3 ct

7.5 mm


3.75 ct

8 mm


5.4 ct

9 mm


7.5 ct

10 mm


10 ct

11 mm


13 ct

12 mm


16.5 ct

13 mm


20.6 ct

14 mm


25 ct

15 mm


31 ct

16 mm


prices for round pearls with good color, lustre and surface;

matched pearls will be worth more as a set

(probably doubling the value of each pearl).

"First grade" pearls are worth about four times

as much as common round pearls.

The prices of 3.75 and 5.4 carat pearls

are from period sources; others are estimates

based on the square-of-the-weight formula.


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