About Gold

For the past several years, the brilliant luster of Gold has fascinated many. Since it was first found it has been a part of our lives. To a lot of people Gold has not just been a precious metal but an investment as well.

Gold is available from earth’s crust, in the seas, river and plants. In nature gold if found in veins and secondary alluvial deposits as a free metal or in combined state. Gold is also recovered as byproduct from Silver & Copper refining.

Placer mining or panning and open pit mining is techniques commonly used to recover gold from earth.

South Africa is world’s single largest gold producer, followed by USA, Australia, Russia and Canada and West Africa.

Physical and Chemical Properties of Noble Metals

Metal Name	Chemical	Symbol Color	Melting	Point Density
Gold	Au	Yellow	1064 C	19.32
Silver	Ag	White	962 C	10.56
Platinum	Pt	White	1773 C	21.45

Purity Standards
Percent	Gold European System	Karat System
100%	999 Fine	24 K
95.83%	958 Fine	23 K
91.6%	916 Fine	22 K
87.5%	875 Fine	21 K
75.0%	750 Fine	18 K
58.5%	585 Fine	14 K
37.5%	375 Fine	9 K

Percent : Parts of gold per 100
Fineness : Parts of gold per 1000
Karat : Parts of gold per 24

NOTE: Karat not to be confused with CARAT, which is used to state the weight of a gemstone. However in INDIA carat normally defines fineness of gold.

Effect of Acid on Metals:

Gold: NO single acid can dissolve or attack directly except in presence of oxidizing agent.
Gold will dissolve in Aquaregia (1 part of Nitric Acid and 3 parts of Hydrochloric Acid)
Gold will dissolve in Potassium Cyanide in presence of oxidizing agent.
An alloy of silver, copper or zinc will attack gold.
Silver will dissolve in Nitric Acid.
Platinum is almost resistance to any acid.

Gold and Platinum have no weather effect. In other words gold and platinum do not rust, tarnish or get corroded. While in case of Silver it will be effected by atmospheric pollution.

The typical composition of 23, 22, 21, 18, 14 and 9 carat yellow, red and white gold alloys.

Typical Composition of Yellow Gold Alloys
Grades in Carat	Metals, Percent by Mass
	Au	Ag	Cu	Zn
23	96.00	4.00	-	-
	96.00	2.00	2.00	-
	96.00	-	4.00	-

22	91.66	8.34	-	-
	91.66	6.20	2.14	-
	91.66	4.10	4.24	-
	91.66	2.00	6.34	-
	91.66	-	8.34	-

21	87.50	12.50	-	-
21	87.50	10.00	2.50	-

18	75.00	16.00	9.00	-
	75.00	12.50	12.50	-
	75.00	11.00	14.00	-
	75.00	9.50	15.50	-

14	58.50	17.50	24.00	-
	58.50	15.00	26.50	-
	58.50	12.50	29.50	-

9	37.50	17.50	42.00	3.00
	37.50	11.00	51.50	-
	37.50	10.50	45.50	7.00

Typical Composition of Red Gold Alloys
Carat	Metals, Percent by Mass
	Au	Ag	Cu	Ni	Zn
	87.50	2.50	10.00	-	-
	87.50	-	12.50	-	-
	75.00	4.00	21.00	-	-
	75.00	2.50	22.00	-	-
	75.00	-	25.00	-	-
	58.50	7.50	34.00	-	-
	58.50	6.00	35.00	-	-
	58.50	5.20	36.30	-	-
	37.50	7.50	55.00	-	-
	37.50	-	61.00	-	-
	37.50	5.00	57.50	-	1.50

Typical Composition of White Gold Alloys
Grades in Carat	Metals, Percent by Mass
	Au	Ag	Cu	Ni	Zn	Pa
18	75.00	15.00	-	-	-	10.00
	75.00	8.00	-	-	-	17.00
	75.00	-	5.00	5.00	-	15.00
	75.00	11.00	3.10	5.90	-	5.00
	75.00	-	5.50	14.50	5.00	-

14	58.50	-	18.00	17.50	6.00	-
	58.50	-	16.50	16.50	8.50	-
	58.50	31.50	-	10.00	-	-
	58.50	21.50	5.00	-	-	15.00
	58.50	18.0	6.50	2.00	1.00	14.00

9	37.50	-	27.60	17.50	17.40	-
9	37.50	-	40.00	10.70	11.80	-

1)	24 Karat -	100 % -	999 Fine
	22 Karat -	91.6 % -	916 Fine
	18 Karat -	75.0 % -	750 Fine
	14 Karat -	58.5 % -	585 Fine
	09 Karat -	37.5 % -	375 Fine

2)	01 Tola =	11.640 gm
	01 Troy Ounce =	31.104 gm
	01 Kilogram =	1000 gm