Today Platinum Group of metals leads the metal table in the trading floor. Out of the six metals in the group five are used in jewellery manufacture. The Platinum Group of Metals (PGM) consists of Ruthenium, Rhodium, Palladium, Osmium, Iridium and Platinum. Osmium is rarely used in jewellery because of concerns expressed regarding its allergic quality. Here is a pre-view of the rest of the metals and the extent of their use in jewellery.
Ruthenium: Symbol is Ru and Atomic Number is 44. Its hardness is assessed as 6.5 in the Mohs’ scale. Melting point is 2,250 Celsius. Density @ 293 K is calculated as 12.2 g/cm3. In the market place, it ranks 5th on the basis of price chart. Crystal structure is hexagonal and colour is silvery. Ruthenium is mainly used as alloy and that also much with Platinum
Rhodium: Symbol is Rh and Atomic Number is 45. Its hardness is assessed as 6.0 in the Mohs’ scale. Melting point is 1,966 Celsius. Density @ 293 K is calculated as 12.41 g/cm3. In the market place, it ranks 2nd on the basis of price chart. Crystal structure is cubic and colour is silvery. Rhodium is mainly used for plating of white gold jewellery. Its other use is for alloying with other PGMs. As standalone jewellery it is not too significant. Nevertheless quite a few articles in the form of wedding bands and rings as well as bracelets are peddled in the gem & jewellery market.
Palladium: Symbol is Pd and Atomic Number is 46. Its hardness is assessed as 4.75 in the Mohs’ scale. Melting point is 1,552 Celsius. Density @ 293 K is calculated as 12.02 g/cm3. In the market place, it ranks 4th on the basis of price chart. Crystal structure is cubic and colour is white. Palladium, next to Platinum is most extensively used metal in the PGMs. Almost becoming a craze amongst the young and old it goes as main metal jewellery in every type of wear including necklace. Like gold it is used for filling and finishing departments. Due to the proscription of nickel over health concerns, Palladium has replaced it in the manufacture of white gold jewellery.
Iridium: Symbol is Ir and Atomic Number is 77. Its hardness is same as Ruthenium at 6.5 in the Mohs’ scale. Melting point is highest amongst the PGMs at 2,410 Celsius. Density @ 293 K calculated as 22. 5 g/cm3 is once again highest for the PGMs. In the market place, it ranks 3rd on the basis of price chart. Crystal structure is cubic and colour is spot white. Possessed of brilliant and shiny white colour, Iridium is used to give an extra finish to jewellery made of PGM group especially Platinum and Palladium. In the case of former, it forms a natural companionship resulting in well-known alloy “IridPlat” which is 90% Platinum and 10% Iridium, a material that is used to turn out eye catching jewellery pieces. On the same page of alloy, Iridium can be used outside the PGM in gold and silver jewellery as well to give fantastic colour and texture.
Platinum: Symbol is Pt and Atomic Number is 78. In terms of hardness Platinum is the lowest amongst the five and clocks 3.5 on Mohs’ scale. Melting point of 1,772 Celsius means lot of hard work at the bench when Platinum is the main metal. In comparison, Palladium is much easier for the fabricators and most often they tend to go for an alloy where Palladium is 20% to Platinum of 80%. Density @ 293 K is calculated as 21. 45 g/cm3 is few points below of Iridium. Most noteworthy feature is that Platinum is ranked as 1st in the price chart not only of PGMs but for all precious metals traded in any metal exchange. Crystal structure is cubic and colour is silvery. Platinum jewellery is known for its sophistry, prestige and perhaps for snobbishness.
Choosing the right metal and appropriate alloy is not an easy task though. Apart from aesthetic and investment value of gem & jewellery, you must also look at the value of cosmics. As you are aware, cosmic energy emitting from gems & metals can make you a successful person. That is only possible when you select the right type of metals that works for you.
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