alloy harness- plat vs whitgold

[mm]

Everyone here seems to say that plat scratches easier than white gold, and also that we should get palladium white golds.

Looking up some harness info on the different plat alloys, i see that:

* plat and iridium (5%) is very soft (80hv)
* plat and iridium (10%) is medium hard (110 hv) and recommended by Mark Morrell
* plat and ruthenium (5%) is hard (135hv), as is 5% cobalt.
* some other plat alloys get up to 300 hv with work hardening.

Most of these values are pretty low compared to the typical nickel white gold (18k) alloys, which range from 150 hv to 220 hv. So I can understand why platinum may scratch easier than nickel white gold.

However, the palladium white gold alloys range from 80hv to 180 hv, with 5 out of seven common alloys being 100hv or below.

So my question is- does platinum really scratch more easily than white gold, or does it depend on which alloy you get?

I understand that the common internet platinum is 5% iridium (including vatche etc etc) and this alloy is very soft- especially as most of the rings are cast (so no work hardening benefits). So is the common use of this soft alloy giving platinum the reputation for being easily scratched?

Also, is white gold getting it''s durable reputation mistakingly based on the hard nickel alloys (which are banned in the EU, and losing popularity in the US), rather than a true reflection of a palladium white golds hardness?

Or am i missing something? Is the lack of self burnishing causing platium to show more scratches? Does self-burnishing really help a white gold that has been rhodium plated?

Sorry for the questions, but I am lookin at a setting at the moment and want to work this one out.

cheers
mm

 

[oldminer]

Harder metals tend also to be more brittle. Ones that are softer scratch easier, but are a bit more forgiving of slight bending in use and seem to hold onto their stones a bit better. Also, the hardness of the metal can be a consideration in the design process. Filigree, open work, type items need hardness to be durable. Heavy, thick items need less hardness as their durability comes due to their weight and thickness.

Gold and platinum are soft metals and their alloys control much about their hardness. However, alloys are not the sole contolling element. A cast item is not as dense as a die struck one. An annealed item is softer than a work hardened one. Rhodium plating does not prevent wear or alter durability or hardness, but it does need to be replaced often as it rapidly wears away. Many people don't rhodium plate platinum, but that is just a mtter of personal taste. There is some new white gold now that is very white and does not need rhodium, but it is not commonly availablel yet. A few years and maybe more product will have this super white, white gold.

Makers like 10% iridium platinum for hand work as it can be adjusted and worked readily. The cobalt alloyed stuff is a pain in the bu** because you need to work on it separately as cobalt creates a very different metal for working. It is amazing how a little alloy changes a lot of a metal's characteristics.

What kind of mounting are you looking for? A tension set diamond requires high hardness. A delicate item may need to be hard, while a heavy item may be just fine in a soft alloy.

 

[tonysgeko]

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On 7/6/2004 11:52:24 AM oldminer wrote:




There is some new white gold now that is very white and does not need rhodium, but it is not commonly availablel yet. A few years and maybe more product will have this super white, white gold.

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Dave, what alloy is being used to makes this new white gold super white? What designers are using this so I can ask to see the line and view it in person? What can consumers do to make the manufacturers aware and perhaps implement this new super white gold sooner?

 

[oldminer]

I believe only Cobb Findings is using this metal right now. This makes it of "interest only" rather than a major commercial enterprise. If the metal is truly super white and durable, it will make its way into the regular world of jewelry. I saw a few items made with it that we said to be not rhodium plated. They sure were like chrome and no yellow. Now, how long that color will hold up is a question we'd want to have the answer to.

 

[Hest88]

Dave, is that the 19K gold or a completely different alloy?

 

[mm]

Thanks dave, I guess I am more interested in the hardness in a durability sense relating to general dings and scratches, rather than in terms of strength and stone holding ability.

The setting I am getting made will be hand made- not cast, so it will be work hardened. It is a princess cut set at 45 degrees in v prongs, with channel set band. I like the idea of platinum as I want to keep the band as thin as possible (my girlfriend has small hands), without losing strength.

I am just afraid that all the threads on here seem to say platinum scratches up more easily, but the numbers seem to say that this should not be the case when comparing most platinum alloys with most palladium WG alloys.

So can you assume that a platinum alloy with a higher harness value will scratch and ding less than a palladium white gold with a lower hardness value?


cheers
mm

 

[Garry H (Cut Nut)]

The hardness / scratching is a bit of a non-issue. Your ring will get scratched. Full stop!
You are almost better off to forget it and wait until you have a few hundred scrathes and then you can not see the scratches for the scratches. That is called a patina.

Work hardening is possible on a wedder, but not on a diamond ring. each time you anneal the ring you undo the work hardening.

 

[Daniela]

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On 7/6/2004 11:29:57 PM Garry H (Cut Nut) wrote:

The hardness / scratching is a bit of a non-issue. Your ring will get scratched. Full stop!

You are almost better off to forget it and wait until you have a few hundred scrathes and then you can not see the scratches for the scratches. That is called a patina.


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This is my opinion exactly. Everything scratches. My platinum engagement ring looks no worse than my 14 k yellow gold promise ring. Scratches happen.

One thing to consider, though, is also that the TOP of the engagement ring will see almost no wear at all as far as scratches go. The top of mine is as shiney as the day we bought it. Do you really care all that much if the bottom of the ring is a little scratched up, especially when gold would do the same thing to some extent anyway?

Get platinum if that's what you think you want for weight and durability. Get white gold if cost is an issue.

 

[mm]

Thanks Daniela, I hadn't considered the issue of where the scratches form.

I have done a bit more internet searching and found an article from the platinum guild that answers my questions. It basically says hardness is a direct measure of resistance to scratches, so we can assume that most platinum alloys (except 5% iridium) would be more resistant to scratches than most of the palladium white gold alloys- which is the opposite to what gets said here a lot.

The most interesting bit I found was a controlled experiment comparing the scratch reistance of different platinum alloys- see below. From reading it, it basically says avoid rings that are cast in 5% iridium if you want to keep a high shine.

Hardness determines a metal's scratch resistance. A recent study by Greg Normandeau and David Ueno published in Platinum Manufacturing Process VIII found that 95/5 platinum/iridium can be scratched and loses its surface reflectivity in a relatively short time, but work hardening will slow down the loss of polish dramatically. It is therefore recommended that jewelry made from 95/5 platinum/iridium should be decorated with surface engravings and other finishes that do not require high polish. The relative softness of platinum/iridium alloys has caused many casters to switch to either platinum/cobalt or platinum/ruthenium for casting.

Platinum/cobalt was created especially as a casting alloy. Its hardness, at 135 HV, makes it relatively resistant to scratching. In the Normandeau/Deno study, it took 2.1 times longer for platinum/cobalt to exhibit the same loss of surface reflectivity as the 95/5 platinum/iridium test sample. (90/10 platinum/iridium fared about the same as the 95/5 platinum/cobalt test sample.)

The Normandeau/Deno study found that the loss of surface reflectivity of 95/5 platinum/ruthenium takes 2.36 times longer than 95/5 platinum/iridium. This makes platinum/ruthenium a good choice for casting as well.

Heat-treatable platinum alloys are another alternative that has become more common recently. These specialty alloys can be hardened through heating to a prescribed temperature. Some can reach a hardness greater than 300 HV. In the Normandeau/Deno study, platinum 950 heat-treatable alloys varied in hardness, but took up to four times as long to lose their shine through scratching.

 

[kevinng]

I was told that there is a chance that micro air bubbles may be introduced into the mounting in the die casting process. These micro air bubbles weaken the mounting. This is especially risky if the air bubbles are in the prong.

Although a diamond ring cannot be work hardened because it has to be annealed, a die struck mounting is still superior compared to a die struck one because there is less chance for air bubbles to be introduced into the prongs.

Is this right?

 

[cardesigner]

Hello, it''s my first post here. Am located in Tokyo and looking at Platinum E-rings. I read the FAQ about Plat alloys, but wasn''t able to post in that forum. Most of the settings I''ve seen in Japan are pt900 alloyed with Palladium, but I''ve read that it''s very soft (80HV). I requested if they could offer a pt900 with Iridium, but so far have only found one shop who was willing to change for $300 extra. I actually prefer some of the other designs, but don''t want to compromise for "inferior" material. Are there any other alloys available in Japan that would be better than the standard Pt/Pd mix?