1 Gold – Gems stone
Pink Color Tourmaline Specimen

Pink Color Tourmaline Specimen

Aquamarine Specimen,Crystal Tourmaline,Green Color Tormaline More »

Blue sapphire gemstone Specimen

Blue sapphire gemstone Specimen

Blue sapphire gemstone Specimen,sapphire crystal Specimen,Tourmaline Specimen,Crystal Tourmaline, More »

Tourmaline Cuts Shapes

Tourmaline Cuts Shapes

Tourmaline Cuts Shapes,Blue sapphire gemstone Specimen,sapphire crystal Specimen,Tourmaline Specimen, More »

watermelon Tourmaline

watermelon Tourmaline

watermelon Tourmaline,Blue sapphire gemstone Specimen,sapphire crystal Specimen,Tourmaline Specimen, More »

Blue sapphire gemstone Specimen

Blue sapphire gemstone Specimen

watermelon Tourmaline,Blue sapphire gemstone Specimen,sapphire crystal Specimen,Tourmaline Specimen, More »

 

Category Archives: Gold

PLATINUM

PLATINUM

Platinum has been used for thousand of years but is was not recog

nized a chemical element until 1735 , of the tree precious matels –gold,silver and platinum –it is the

rarest and the most valueable .chemically innet and resistant to corrosion , platinum doesnot tarnis

h when exposed to the atmosphere ,unlike silver.It is silvery grey ,grey-white, or white in colour

, opaque , and has a metallic lustre it is slity more dense then pure gold and twice as dense as silver early jewellery had difficulty achieveing the 1,773oc  (3.223OF) needed to melt platinum ; it was not until the 1920s that the technology

was developed sufficiently to work this precious metal .

OCCURRENCE:Platinum  forms in  igneous rocks, usually as ores in which the grains of platinum are often too minute to be seen with the naked eye. It may also  occur in secondary “placer”deposits in river sands and gravels ,and glacial deposits- usually are grains ,more rarely as nuggets. The main occurrence of platinum have been in South Africa ,Canada (Sudbury ),the USA (Alaska) ,Russia ( the River perm and other rivers running down from the Urals),Aistralia ,Colombia and Peru .

REMARK : Although nuggets had been set in rings 1920 ,most platinum jewellery dates from after this time .Soft and easy to work ,platinum is often fashioned into quite intricate designs.

Silver

SILVER

COLOUR : Silver

COMPOSITION :Ag

CRYSTAL STRUCTURE :cubic

HARDNESS :2.5-3 specific gravity :10.1-11.1

LUSTER:Metallic

TRANSPARENCY :  Opaque

 

Silver usually occursin massive form as nuggests or grains, although it may also be found in wiry ,dendritic (tree-like) aggregates .when newly mined or recently polished ,it has a characteristic bright ,silver-white colour and metallic lustre .However,on exposure to oxygen in the air a black layer of silver oxide readily forms,tarnishing the surface .Because of this ,and the fact that it is too soft to be used in most jewellery in its pure form,silver is often alloyed with other metals ,or given a covering layer of gold and silver in use since the time of the Ancient Greeks contains 20-25 percent silver. Sterling silver  contains 921/2percent or more pure silver (and usually some copper) ,and Britannia silver has a silver content of 95 percent to more . Both alloys are used as standards to define silver content .

OCCURRENCE:Most silver is a by-product of lead mining ,and is often associated with copper .The main silver mining areas of the world are South America,the USA,Australia ,and the former USSR .The greatest single producer of silver is probably Mexico ,where silver has been mined from about AD1500 to the present day . The finest native silver ,which occurs naturally in the shape of twisted wire, is from Kongsberg ,Norway.