Gold
Gold is a beautiful yellow metal; thin gold (verdigris gold) has a greenish tint. Gold forms chemical compounds with difficulty, it is chemically stable in air, water and acids, except for aqua regia (in which gold dissolves forming gold hydrochloric acid). It also reacts with free chlorine ions, potassium and sodium cyanides, bromine and some other chemicals that have no application in the jewelry industry. The density of gold is 19.32; melting point 960 degrees C; hardness on the Mohs scale 2.5. Gold has high reflective ability and polishes well; it has high malleability and can be rolled into sheets as thin as 0.0001 mm. Thermal and electrical conductivity of gold is lower than that of copper. Its specific heat capacity is relatively low, due to its low hardness and strength, gold is used in jewelry in the form of alloys with other metals and very rarely in pure form1
of the Russian Customs Service dated 20.01.1999 No. 01-15/1361 "ON THE ISSUANCE OF INSTRUCTIONS AND METHODOLOGICAL RECOMMENDATIONS" (together with "INSTRUCTION ON THE PROCEDURE FOR TRANSFER, ACCEPTANCE, ACCOUNTING, STORAGE AND HANDOVER OF ITEMS RECEIVED FOR EXPERTISE IN CUSTOMS LABORATORIES AND CONTAINING PRECIOUS METALS AND PRECIOUS STONES", approved by the Russian Customs Service 11.01.1999 No. 01-23/1359, "METHODOLOGICAL RECOMMENDATIONS ON THE PROCEDURE FOR CONDUCTING AN INSPECTION OF JEWELLERY ITEMS CONTAINING PRECIOUS METALS AND STONES WITH THE PARTICIPATION OF A SPECIALIST AND REFLECTING THE RESULTS IN THE PROTOCOL", approved by the Russian Customs Service 11.01.1999 No. 01-23/1360) ↩