Here at Walker Goldsmiths we use precious metals every day and even though metallurgy is a science we often feel we are dancing with our materials to get the desired results. Gold (Au) and silver (Ag) are the precious metals. Platinum (Pt) is often added to that list and while platinum is a precious metal it comes with a group of cousins usually referred to as the “platinum group”. It is like people referring to us as that Walker Group, because there are a lot of us and some of us have names that are strange to people who don’t know us very well. The Platinum group are metals with similar properties that are usually found together and in fact are hard to separate. When you look at the periodic chart of the elements you will notice that copper (CU) silver and gold are arranged in a vertical line, and all three have very similar physical properties. Such as malleability, ductility and resistance to corrosion. Now go one column to the left and we have nickel(Ni), palladium(Pd), and platinum, another jump to the left and we have cobalt(Co), rhodium(Rh) and iridium(Ir). Sometimes ruthenium (Ru) and osmium (Os) are included in the group but they are both quite rare and have little or no commercial value
Rhodium is used to electroplate nickel white gold to make it look whiter as nickel is a yellowish white and rhodium is a blue white that looks great in a display case! Palladium is used to alloy with gold to make palladium white gold which is the white gold of choice in our studio as it has a pleasing blue white color and never needs to be plated to look good. It is a little more expensive as palladium is more expensive than nickel. Iridium is the next member of the family and is often used as an alloy for platinum (10%Ir, 90% Pt). I have never seen Platinum alloyed more than 10% used in jewelry so when you get an article that is stamped PLAT it is at least .900 fine and is often stamped with the alloying metal cobalt or iridium or palladium as well. This is the big reason that Platinum jewelry is more expensive than gold jewelry, even when gold and platinum are nearly the same price gold is usually alloyed to 14K (.585 gold) while Platinum is usually .900 fine. There are also some manufacturing considerations. Platinum has a very high melting point at 3215 degrees F. It takes some special equipment to cast platinum jewelry so we do not do this in our studio. We do fabricate some simpler designs in platinum and I have learned to love the welding properties of this amazing and beautiful metal. If you have questions ask them in the comments section and I will respond.
We now set all diamonds of any size in Platinum crowns, and when customers come to us with a worn crown that needs retipping we encourage them to pay a little more and get a platinum crown as it will never need retipping. Platinum has the amazing property of abrasion resistance. When you cut it with a saw or a graver or a file it feels SOFT, but then you go to polish it and it takes forever! We even have special polishing compounds just for polishing platinum. If your diamond needs tips get a new platinum crown from Walker Goldsmiths and have it reset into platinum. You will not regret it!