Today we measure gold in grams and kilo grams. Since ages gold was measured in terms of ‘Tola’. In British system 80 Tola = 1 sher (910 grams). Tola was subdivided in 100 parts which was knowns as ‘Gunj’ . World’sstandard for goldmeasurement is troy ounce, which is French in origin. Even today gold is quoted in USD per troy ounce (31.103 grams). Tory ounce was subdivided in to grains (435.5 troy grains), traditionallybarley grains. Surprisingly both in ancient India as well as Europe, gold was measured with agro produce.
Quest for gold purity has been a puzzle for mankind. Oldest method was put forward by Archimedes (287 BC to 212 BC). King handed him a golden crown to test its purity. Crown had beautiful motifs and was to be handled delicately without any damaging. Floating in a bath tub, he found his principle and could device method to check density of the crown by submerging it in the water. He found out that crown was not of pure gold as density of the crown was less than pure gold. Later on some machines were marketed to test gold purity on density principle.
Karatometer is comparatively a new instrument. In bygone era, gold purity was tested on black siliceous rock. Line was drawn by the ornament on the rock. Experts looking at the line could tell gold purity within 2%. Method was highly subjective and depended on the expertise.
Gold purity is measured in Karat, 100% pure gold is call 24 Karat. 24 Karat gold is very malleable and for ornament purpose 22k is used. For hardness and for holding gemstones European and American designers use 18 k gold. For low cost designers has use as low as 7k gold for small ornaments.
Many countries have introduce commemorative gold coins with gold content of 1 tory ounce. Most famous are :
|United States||Saint-Gaudens Double Eagle|
|United States||American Gold Eagle|
|Canada||Gold Maple Leaf|
|United States||Indian Head Eagle|
|United States||$3 Princess|
India historically has gold coins since Kanishka kingdom and his prodigies, Gupt dynasty and few other dynasty. The gold coins were coined on events like coronation, marriage or important victory. Gold and silver coins minted in 1540 and continued to be minted till 1947 were Mohur (gold 10.95 grams) and Rupiya (silver 11.53 grams). Coins were traded right from Afghanistan to Indonesia and even today Rupee is standard denomination in many counties including, India, Pakistan, Nepal, Shri-Lanka and Indonesia.