The Breitling Watch Source Forums

Hi
Just polished my platimun wedding band with a cape cod. It did not remove all the scratches but it has a good polish to it. Suffice to say it looks 100% better.

Jiggy

I'm not disputing science, it's clearly a fact that Platinum is harder than Gold in it's RAW NON JEWELRY FORM! But that wasn't the question, I'm quite sure bozman wasn't asking to use a cape code cloth on a raw piece of platinum that he uncovered in his yard. In Jewelry form, Platinum is SOFTER THAN GOLD. Here are just a few jeweler websites confirming this fact!

http://www.goldenet.com.au/m_gold_explain.aspx
http://www.andrewsjewelers.com/platinum.php?eid=4
http://www.foxfirejewelers.com/white-gold.html
http://www.hannonjewelers.com/metals2.html

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"I don't own any watches, I just lease them"

I suspect that we are boring people, so this will be my last post on this.....

Link 1 - quote "Platinum is also easier than gold to hand engrave as is softer than gold." - that doesn't confirm any fact - it's just words - and it's followed by "Due to platinum being more durable and longer lasting it is obviously more expensive. Thus if platinum can be afforded, it is always highly recommended." Rather confusing at least

Link 2 - I didn't get past "During the final steps of the manufacturing process the more yellow looking white gold jewelry is dipped and electroplated in rhodium, which is a form of liquid platinum. In essence, white gold jewelry is simply yellow gold jewelry with a platinum skin. Over time however, the rhodium wears off and the yellow surface below bleeds through and the jewelry appears to tarnish. The tarnished look can be removed by replenishing the rhodium plating and most local jewelers can do this for a fee of $25 to $50. The typical white gold jewelry item must be re-plated once every 6-12 months." Rhodium is an element in the platinum group, it is not a form of platinum, and as anyone with white gold knows you do not need to replate it every 6 to 12 months.

Link 3 - another comment with nothing to back it up, quote "Another aspect of platinum is durability. Because platinum is actually softer than gold alloys it has excellent resistance to wearing away in jewelry. On a microscopic level, platinum dents instead of chipping off like white or yellow gold. While this makes platinum very durable it also means it dulls more quickly in wearing."

Link 4 - this actually has some scientific merits, and is much better than the misinformation in the first three links. However it still doesn't provide a scientific basis for the comparison. I will agree that some white gold alloys can be harder than platinum alloys - I said yesterday that gold can go over 200 on the Vickers scale that you don't approve of, but it's not automatically the case, and is generally lower.

I have nothing more to say.

OK, I lied - this is my last post on this subject.

The Vickers hardness test is recognised as one of the standards for measuring the hardness of metals - http://en.wikipedia.org/wiki/Vickers_hardness_test

White gold is an alloy made up of gold and other metals. White gold is commonly made with nickel, palladium, manganese or even silver (as well as other metals - copper, zinc, etc). Nickel is used less than it used to be because of the prevalence of nickel allergies.

Regardless of blends white gold (and other golds - white gold is just the typical comparison with platinum) has a Vickers hardness rating of around 125 (generally 125 - 130 depending on exact mixes) - http://gilletts.com.au/information.php?info_id=39, http://www.mokume-gane-metals.com/faq.html#Q9, http://www.tamanie.com/jewellery_care.html

Platinum is more difficult because unlike gold, the different metals used to alloy with it result in a very different product. Part of that is that platinum is assayed based on weight - 950 platinum is 95% platinum by weight, but that means that if it is alloyed with a lighter metal then the volume of platinum will be far less than if it is blended with a heavier metal.

The three major 950 platinum alloys are with iridium, ruthenium and cobalt. Less than 95% (950) and it can't technically be called platinum - http://www.allaboutgemstones.com/metal_ ... tinum.html

Iridium is the heaviest of the three (almost the same as platinum) so 950 platinum with iridium is around 95% platinum by volume and therefore relatively soft (like pure platinum) - a Vickers rating of 80. Ruthenium is not much more than half the weight of platinum so 950 platinum with ruthenium is almost 10% ruthenium by volume and has a vickers rating of 135 (may be slightly lower at 130, depending on the method used to produce). Cobalt is only about 1/3 the weight of platinum so platinum is only about 84% by volume. This also has a vickers rating of 135. All of this is covered very well here - http://www.mwmjewelry.com/platinum_purity.htm. Second source here - http://www.weddingbandsuperstore.com/platinfo.html

So, with a hardness standard (Vickers) we have (soft to hard):

950 platinum (iridium)
18k gold
950 platinum (ruthenium)
950 platinum (cobalt)

900 platinum with 10% iridium is also worth mentioning as it is a good jewellery metal - the higher iridium content stabilises it, but (in North America at least) 900 platinum cannot be called platinum, it has to be called iridium platinum so is less popular (despite having more platinum by volume than the cobalt alloy).

While 950 platinum with iridium is well liked by jewellers because it is so easy to work, it is not popular with consumers (because it is so soft) - it doesn't age very well. This link again - http://www.mwmjewelry.com/platinum_purity.htm, so ruthenium and to some extent cobalt are far more popular.

950 platinum with iridium is used a lot for anodes and electro-catalysts - that get's real scientific, real quick, but Google can help you with the science if you really need it.


Apologies to those that I have bored, but I wanted to at least get the science out there. I really am done now.

Roff, I appreciate the thoroughness of your reply. I know more about platinum than I ever hoped for, but I'm still not sure if I can use a Cape Cod . . .

I think I'll just let the jeweler mess with it.

-Craig

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Chronomat 01- Sierra Silver/Steel
Navitimer 01- Limited Edition #1337/2000

Sorry to disagree here but my wedding ring needs to get re-plated once a year, I really hate white gold. So does my wife's ring, as far as how hard platinum and gold are, I have no idea and really couldn't care less.

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"Leave the gun, take the cannoli."

One final response to Mr Wizard's chemistry lesson. While 950 platinum w/iridium may not be the consumers popular choice, it is howevever, the most common formula for platinum jewelry......therefore it would be safe to say that the majority of platinum jewelry is softer than gold.

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"I don't own any watches, I just lease them"

Not sure that there is a 'standard', but most jewellers will say 12 - 18 months, so the 12 months part of the comment I have no issues with - 6 months is a rip off.

That said, it does also depend on the other metals - now we are getting into territory that I don't know about, but anecdoatally I have a three colour wedding band and the white is holding up very well after 13 years and no replating.

I certainly don't want to get involved in the heavy metallurgical debate from the earlier part of this thread, but I was always under the impression that only certain grades of white gold ever needed to be replated with rhodium to restore the shine. It all depends on the metals used in the alloy whether additional plating is required. I'm guessing it's a peculiarity of the type of white gold used in jewellery because my fathers wedding ring also needed replating, whereas I've never come across a modern white gold watch case that ever needed it.

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Driver8

Site Moderator

I do a lot of work on electronics and working with my hands a lot and also use different types of chemicals and other crap that messes up the plating on my ring and that actually does screw it up quicker than 12 months, I just wait 12 until my wife brings it in to get hers taken care of. If you don't wear it doing manual labor or while using any kinds of chemicals it'll last longer.

Anyway, back to platinum.....

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"Leave the gun, take the cannoli."

i use cape cod cloth on my platinum wedding ring all the time.

it doesnt take scratches out like it does on stainless steel...but it does polish it up nice and shiney.

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ROLEX SEA-DWELLER DEEPSEA

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Breitling for Bentley 6.75

I find the Cape Cods are pefect for restoring a rosey complextion to my cheeks. Lasts for weeks.

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SHARKMAN

I was once told that when platinum is polished that you do not "lose" a layer like gold, steel etc. I was told that the platinum "moves" and "spreads across the surface" any truth to this?

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sco
Breitling Chrono Superocean
Omega Aqua Terra 8500
Rolex Submariner Date Ceramic

Yes.

It's complex molecular bond stuff that I really don't fully understand, but short answer - yes