some metal facts you might not know

Gold and platinum are alloyed with less costly metals when making the karat quality used for jewelry.  Most platinum jewlery is 95 to 90 percent platinum with the balance an alloy.  Some new platinum products are 50% platinum and 50% less costly metal although some is alloyed with palladium which is hardly "cheap", but less costly than gold or platinum.
Gold is alloyed with many different metals, all of which cost way less than gold.  All alloys are substantially lighter, a lower specific gravity, than pure gold or pure platinum.

When we hear that 18 karat gold is 75% gold we rarely give it a second thought.  Or if we hear of 50% platinum being made of 1/2 platinum and 1/2 another metal we don''''t think a lot about it.

Here''''s the strange part.  Metals are alloyed by WEIGHT, not by VOLUME.  The alloys for gold and platinum are MUCH lighter than gold or platinum.  It takes quite a bit more volume of alloy metal to mix in to make any karat of gold or platinum than one might think.

By volume, 14kt gold, is quite a bit less than 50% gold content.  By volume, 50% platinum is far less than 1/2 platinum and 1/2 alloy.

It is the classic situation of mixing feathers with lead to get a 50-50 ratio of content.  A few drops a lead and a container full of feathers makes 50% of each by weight, but the composite lead/feathers when examined buy VOLUME is nearly all feathers with just a spot of lead mixed in.

Platinum and gold when pure don''''t tarnish.  It is always the alloy that tarnishes anyway.  That'''' s why 14kt gets a patina faster than 18kt.  The amount of alloy content that can tarnish is a lot higher in 14k than 18k.  The new platinum/palladium mix may not tarnish because pure platinum and pure palladium don''''t tarnish.  I suppose when mxed, they still will not oxidize.

Anyway, food for thought.  I always loved making karat gold when I did shop work many years ago.  Glowing, flowing metals, the hissing of the torch, the smell of the burning and the bright metal when it finally cooled.  When you see the amount of alloy in a 14kt gold unmelted pre-mix, you''''d really be surprised.