Monday, June 13, 2011

The Carat: Indian Gold Measurement System

The carat (abbreviation ct or kt) is a measure of the purity of gold alloys. In the Unite States and Canada, the spelling karat (abbreviation k or kt) is used. The carat is a unit of mass equal to 200 mg and it is used for measuring gemstones and pearls.

1g = 5 ct

As a measure of purity, one carat is 24 times the purity by mass:

X = 24 Mg/Mm

where

X is the carat rating of the material,

Mg is the mass of pure gold or platinum in the material, and

Mm is the total mass of the material.

Therefore 24-carat gold (Au) is fine (99.9% Au w/w), 18-carat gold is 75% gold, 12-carat gold is 50% gold, and so forth. The most common carats used for gold in jewelry making are:

ü 24 carat (millesimal fineness 999 or higher)

ü 22 carat (millesimal fineness 916)

ü 21 carat (millesimal fineness 875)

ü 20 carat (millesimal fineness 833)

ü 18 carat (millesimal fineness 750)

ü 15 carat (millesimal fineness 625)

ü 14 carat (millesimal fineness 585)

ü 10 carat (millesimal fineness 417)

ü 9 carat (millesimal fineness 375)

ü 8 carat (millesimal fineness 333)

ü 1 carat (millesimal fineness 042)

Millesimal fineness is a system of denoting the purity of platinum, gold and silver alloys by parts per thousand of pure metal by mass in the alloy.

For example, an alloy containing 75% gold is denoted as "750". Many European countries use decimal hallmark stamps (i.e. '585', '750', etc) rather than '14K', '18K', etc., which is used in the United Kingdom and United States.

22/22K - a quality mark indicating the purity of gold most popularly used in India. This purity was adapted and practiced by the big jewellers and was later passed to jewel smiths. The first 22 signifies the "Skin purity", the purity of the top layer of the gold jewelry, and the second 22 signifies that after melting purity of the gold jewellery will be 22-carat, or 91.67% of pure gold. This system is used to show consistency in the quality of the gold.

This practice was pioneered and introduced in the early mid-1980s by Nemichand Bamalwa & Sons of Kolkata, India, sparking a revolution in India as it forced jewellers to indicate correctly the after-melting purity, and heightened consumer awareness made it a most sought-after stamp or quality mark.

This symbol or stamp is very popular on the gold jewellery business in Asian countries like India, Sri Lanka, Pakistan, Bangladesh, Nepal, Yemen, and Persian Gulf countries.

Ratti

A ratti is a traditional Indian unit of mass measurement, and has now been standardized as 0.12125 gram. It was measured by ratti seed. This seed is actually Abrus precatorius seed, known commonly as Jequirity, Crab's Eye, Rosary Pea, Indian Licorice, Akar Saga, Giddee Giddee, is a slender, perennial climber that twines around trees, shrubs, and hedges. It is a legume with long, pinnate-leafleted leaves. It is also known as Gunja in Sanskrit and some Indian languages and Ratti in Hindi. The plant is best known for its seeds, which are used as beads and in percussion instruments, and which are toxic due to the presence of abrin. The plant is native to Indonesia and grows in tropical and subtropical areas of the world where it has been introduced. It has a tendency to become weedy and invasive where it has been introduced.

· 1 tola = 12 masha or 11.67 gram

· 1 masha = 8 ratti or 0.97 gram

Masha

A masha is a traditional Indian unit of mass, now standardized as 0.97 grams.

Tola

The tola is a Vedic measure, with the name derived from the Sanskrit tol meaning "weighing" or "weight". One tola was traditionally the weight of 100 ratti (ruttee) seeds, and its exact weight varied according to locality. However, it is also a convenient mass for a coin: several pre-colonial coins, including the currency of Akbar the Great (1556–1605), had a mass of "one tola" within slight variation. The very first rupee, minted by Sher Shah Suri (1540–45), had a mass of 178 troy grains, or about 1% less than the British tola. The British East India Company issued a silver rupee coin of 180 troy grains, and this became the practical standard mass for the tola well into the 20th century.

1 comment:

  1. Thanks for this information about carat.Indians just love jewellery.For them its a part of their ancient traditions and customs.Women desires for precious ornaments,18 k gold jewellery and diamonds.

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