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Choosing Between 14k, 18k, Palladium And Platinum


blinger.mike
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Im getting ready to purchase a new ring for my wife. I have been looking all over for some good descriptive write ups on the color, finish and hardness or durability of each metal and haven't really found anything that good. I was also trying to find something that talked about when each metal would be do for a re dip and polish and how each metal reacts to this process. I have found a lot of people giving their opinions but haven't found a real comparability chart that stacks the metals against each other and gives pro"s and con's to each metal. Im not concerned with price or resale really and I understand that setting style, hypoallergenic metals and everyday use matter but is there anything that breaks it down for a consumer that would allow them to make a decision that jives with their life style and concerns?

 

I know there may be a lot of other reasons for picking a metal, but as a guy Im concerned with the ones I listed and would love some real technical data about each category listed as it pertains to each metal. For example do these metals have a MOHS hardness rating? Why 18K when it is softer than 14K?

 

Thanks :huh:

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One of the reasons why you haven't found anything which clearly states things in a comparative fashion is because there's so many variants and alloys - not to mention relevant properties to the questions you put - that listing them all in a way that is understandable is pretty much impossible; in addition, new metallurgical developments keep coming on (e.g. non-tarnishing alloys for silver, magnetic platinum alloys, heating-sensitive alloys, ...). I'll write my $0.02 below, trying to answer your questions - please bear in mind that what follows is a broad generalisation, and exceptions can and will be found to almost any statement below.

 

Colour:

Platinum and palladium are naturally grey-white. White gold (I assume you are talking of WG only) may need plating, depending on the alloy used, but some alloys are also grey-white (if usually darker than Pt/Pd).

 

Finish:

It's more a matter of workmanship than anything else. All the metals will polish nicely, and are adaptable to a variety of finishes, however platinum requires the highest number of steps to polish properly, and gold the least. Plating on WG may hide some of the surface imperfections.

 

In terms of frequency of repolishing/replating, two things to bear in mind: 1. only some WG alloys will require re-plating; 2. there's no accounting for taste. Platinum and palladium will develop patina - i.e. a change in colour reflecting usage patterns, while WG is less likely to (partly because Rhodium plating is quite hard, partly because WG gets replated, and partly because gold wears faster). I love platinum patina, and I'd much rather have that than a highly polished piece; others hate it and want a mirror-bright surface at all times.

 

Hardness:

In metals it's not measured using Mohs's scale. The most diffused measurement is hardness measured on the Vickers scale (HV), which is the standardised measurement of how much a pyramidal punch will penetrate a sample of the material. On this scale, the annealed metals (in the most commonly used alloys) measure as follows:

 

18K WG: 80 - 220

14K WG: 100 - 165

Pt: 60 - 135

Pd: 90 - 150

 

The working process may produce metal which is considerably harder (but not softer) than the values above. The wide variations are due to the other elements in the alloy, and other alloys may well have properties outside that range. Bear in mind that a hard material is not necessarily a strong or durable one: first of all, tensile strength (the ability of the metal to be stretched without breaking) is not directly proportional to hardness, and secondly other properties are also important. For example, plasticity: in general gold is springier than platinum or palladium, but it's also more brittle. As a result, if a gold object is banged against something it may not be dented, but it may crack; platinum is more likely to be deformed but remain "whole".

 

Repairability:

Platinum and palladium tend to "furrow" when scratched, so metal remains there and can be smoothed in with a polishing process as long as the polisher doesn't use abrasives. Gold tends to chip when scratched, which means metal is lost more easily. On the other hand, gold alloys generally melt and are workable at temperatures which are about half of those used for platinum (and palladium is pretty close, if slightly lower), which means more jewellers will be able to repair items in gold and stones etc. will be less affected. Palladium is the most reactive of the three metals (though much of the reactivity of gold will depend on the other components of the alloy), so it requires some caution, particularly in mixed metal pieces (e.g. cadmium-free solders), to avoid durability problems. The much greater diffusion of gold and platinum may mean that finding a competent person to repair palladium properly is more difficult.

 

18K vs. 14K gold:

Cost/snobbishness/fashion - 18k is 75% gold, 14k is 58.5% gold. Some people feel it's not enough "precious metal". In terms of physical properties, you can pretty much find what you want in either purity, but achieving some characteristics may cost more in one karatage than the other. Also, 14k may contain more allergenic substances, since the amount of gold is lower.

 

HTH

Edited by davidelevi
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Hey recently I was shopping around for an engagement ring and I also had a hard time choosing between all the different metals. I would read a lot of different opinions, but since I did do a lot of research I came across this chart, hope it helps.

 

http://novelldesignstudio.com/choosing_your_metal/index.php

 

Yeah I saw this in another post about metals. Nicely done chart but way to vague for me. I do find it interesting that they call these points facts though?

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Fairly wrong facts - palladium has consistently been worth less than gold in the last 20 years except for the years between 1998 and 2002. In terms of purity, titanium is not alloyed (except for minimal amounts), and neither is tungsten (assuming they aren't talking about tungsten carbide, which is not a metal anyway). And as far as allergies go, gold alloyed with palladium is about as hypoallergenic as anything else.

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