Help!! PT 950 with 5% Ruthenium

[swingdoctor]

As I understand this is the best combination in terms of durability, relative resistance to scratches and "strength". I''ve been looking and I can''t seem to find anyone in Melbourne, Australia or Singapore (where I will be holidaying soon) who uses this particular alloy. Most companies who use platinum don''t advertise the type of alloy that they use. Could someone help me out here? Finally does it matter how its cast? Thanks.

 

[PhillipSchmidt]

Hi Swing,

Ruthenium alloy is very rare in Australia - unheard of except I know of an importer who buys casting that is made from it occassionally. It was used in the UK, though not all that popular. Cobalt alloy is the most common here by far! One firm in NSW casts with an Iridium/platinum group mix that they advertise as the best alloy world wide. It is good but their ''raw'' stock guage is excellent and beyond par. The thing is, platinum is not very popular here with retailers so they don''t push it and in general, they don''t care to offer the best.

Ruthenium is OK. It is hard to polish, the results are Ok, but arguably not worth the effort. Best results are found elsewhere. Ruthenium polish should last very well, but the best polish and colour is found elsewhere.

I am not sure what is on offer in Singapore?

Phillip

 

[diamondsrock]

platinumsmith,
could you go over the various combinations (ruthenium, iridium, etc.) and how they would stand up to wear and tear on a plain wedding band? I wil be shopping for one for my husband and I thought ruthenium would be the best but I don''t know. Does it even matter? I want the metal to be hard and resistant to scratches. Thanks!

 

[Scintillating]

Date: 9/1/2005 10:12:02 AM
Author: Platinumsmith
Ruthenium is OK. It is hard to polish, the results are Ok, but arguably not worth the effort. Best results are found elsewhere. Ruthenium polish should last very well, but the best polish and colour is found elsewhere.
Phillip

Platinumsmith,
Could you tell us a little more about a Ruthenium alloy?
I thought this alloy looked a little grey.
Does it hold High polish well?
Anything else you can tell us?

Scintillating...

 

[PhillipSchmidt]

What I want to say is hard to put in words without a background. It is just practical knowledge. There was a fairly comon consensus of oppinion aongst other tradesmen though. I am afraid that when things get intelectualised, everybody becomes an expert and debates brew that are weighted all out of proportion. I have had customers demand they have ruthenium which is ok, but they have seen a set of figures and made judgemenst on that alone and know nothing of the real practicalities that come into play.

Anyway, here is a thread on alloys that you should probably have a look at.

I''ll add a bit about ruthenium later.

Phillip

 

[Scintillating]

I thought this was interesting.
It''s what Mark Morrell says about Platinum alloys.

Scintillating....

 

[PhillipSchmidt]

Some practical experiences I have had with ruthenium alloyed platinum

I worked as a diamond setter, assembler, etc in the UK for the trade. The area that I worked in has more then 2500 jewellers. I often set diamonds and polished ruthenium alloyed platinum. I saw a lot of other platinum jewellery with other alloys.

One casting house that we often used produced a ruthenium alloy. They had periodic problems with porosity, but they had a laser welder at call, so if the porosity didn''t show until too much work had been done, it could be fixed. The porosity problem was worse then most other casting houses - using other alloys; better or worse, but the good service made them a good choice regardless.

The ruthenium castings were always rough and we expected that it would take a lot of filing to get the right form. I was working on a high turnover and I typically produced hand carved waxes & waxes produced by CAD CAM. I made my designs heavy, expecting to refine the design in platinum. (Nowadays, I cast a wax in silver and perfect the design before I make a mould and this extra step ensures the casting will be exactly how I want it to be and I get better results here then I had before). Casting a wax can create a lot of waste in platinum.

I used to work with ruthenium quite a lot. The castings were relatively poor, but that metal was viable in my situation - see above. I must admit I did like the hardness and it was good for that reason, though I can’t say I had a chance to alter my designs to use the extra strength, because the castings were so bad. I understand that they were not getting the investment right (casting term, don''t worry) and the castings should have been better, so perhaps somebody, somewhere is casting; fine 4 claw settings in ruthenium, which can’t be done in other alloys, but I don’t know about that. I suppose if you are that fussy, then you should go for hand wrought manufacture and pay the extra for the increased labour and waste. That is, if the absolute best results are wanted.

Personally I like almost any good clean platinum stock gauge; say 6mm square wire - raw material.

If I had to choose a casting medium I would choose (not in this order) 900 plat + 100 iridium (safe bet for the average fussy consumer), or a good 950 plat + (e.g.) 20 iridium + ruthenium + rhodium etc – quantities and methodology unknown (though the 950 stamp is a good thing), and then cobalt, then ruthenium (done properly) & you can probably discount the rest.

I prefer platinum group metals to be alloyed together for best results, but then there is copper and it was the best alloy (for hand wrought jewels) available until recently. I have never heard of it being cast, but I dare say it is added to cobalt/ruthenium etc with varied results. Gold is added too, with poor results.

Metallurgy is not logical to me, but such are the laws of nature. I understand that all the studious people involved in the field of precious metals have the same problem and every discovery is made by trial and error and many platinum alloy successes are kept as guarded secrets, at least for now.