Platinum Guru

Burnishing Platinum

If you discover porosity on a piece, remove it through burnishing or hammering (in some cases it might need to be filled).  To burnish the edges and surfaces, use a highly polished tungsten carbide burnisher and light oil as a wetting agent.  Platinum burnishes well, but be careful; the burnisher will immediately begin dragging any debris left on the surface, resulting in scratches.

You can reduce scratches even further with a gray polishing compound, followed by a white compound and then by orange, green, or carrot rouge to get the highly reflective luster for which platinum is known.

-Jurgen

Making Platinum Jewelry,Setting Gemstones,Bench Jewelers

Finishing Platinum

A typical finishing sequence for platinum begins with filing the surface, using a #4 cut file.  Cross-file the metal diagonally without excessive pressure and without reducing the original surface.  Repeat this procedure with a #6 file.  When filing a curved surface, follow the curve to avoid creating flat spots.

After filing, remove the file marks with abrasive paper.  Start with 240 paper, followed by 320, 400, and 600 papers in succession as needed.  Silicon carbide or aluminum oxide papers are preferred.  You can also find diamond-coated papers on the market that work well; they range from 220 to 50,000.  As an alternative to the 400 and 600 papers, you can use a unitized (compressed fiber) wheel, which also comes in different grades.

- Jurgen

Making Platinum Jewelry,Setting Gemstones,Bench Jewelers

Polishing Platinum

After sizing and setting, you are ready to finish the ring.  When platinum is polished properly, it will take on a shine that no other metal can produce.  Platinum does not oxidize, nor is it affected by atmospheric conditions.  This ensures a good, long-lasting finish, but it takes some effort to achieve maximum results.

As a general rule, polish as much as you can prior to setting or assembly.  Also, if platinum is being joined to gold, it’s important to finish the platinum section first.  Failure to do so will result in over polishing the gold portion of the piece.

-Jurgen

Making Platinum Jewelry,Setting Gemstones,Bench Jewelers

Setting Stone in Platinum Bezel

When setting a stone into a platinum bezel, make a bright cut at a 45º angle along the bezel’s inside edge, after the seat has been made.  This way, as the bezel’s edge is rolled over for hammering around the stone, the shine will extend all the way to the girdle.  You’ll then be ready for the final bright cut of the bezel without the need to cut too close to the girdle and possibly damage the stone.

-Jurgen

Making Platinum Jewelry,Setting Gemstones,Bench Jewelers

Pave Setting in Platinum Jewelry

When you have a pave’, bead, or bright setting job, drill small pilot holes that can then be enlarged.  This will take more time, but it’s worth it as it provides a margin for error.  For example, if you have a honeycomb layout with 144 holes positioned side by side, you could drill every hole the exact size you need-but any drift in the drilling process will ruin the entire layout.  By using a smaller drill, you can correct any drift as you enlarge each hole.

-Jurgen

Making Platinum Jewelry,Setting Gemstones,Bench Jewelers

Stonesetting

Platinum has the distinction of being called a “dead” metal, which means it has very little or no memory.  When a platinum prong is pushed into place, it usually stays there without sag or spring.  However, platinum also tends to fill up the grooves of drills and burrs, so some care must be taken when you begin setting stones.  Use only sharp, well-lubricated drills.  When using a burr, make sure it is either new or well cleaned.  Also, use well-polished gravers for pave’, bead, and bright settings.  I recommend tungsten carbide gravers, since they hold their polish better and retain a sharpened edge.

-Jurgen

 

Making Platinum Jewelry,Setting Gemstones,Bench Jewelers

Platinum Fabrication Techniques

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FTC Guide for Marking Platinum Jewelry

The FTC Platinum Guide for marking jewelry made wholly, or in part, of platinum provides that items consisting of:

*  950 parts or more per thousand of pure platinum can be marked "Platinum" without the use of any qualifying statements;

*  850 to 950 parts per thousand can be marked in accordance with international standards of "950 Plat." or "950 Pt.," "900 Plat." or "900 Pt.,"

*  "850 Plat." or "850 Pt.”  (The revised guide permits the use of a two or four letter abbreviation for platinum);

*  500 parts per thousand of pure platinum and at least 950 parts per thousand platinum group metals can be marked with the parts per thousand of pure platinum, followed by the parts per thousand of each platinum group metal (example: "600Plat.350Irid." or "600Pt.350Ir.” and less than 500 parts per thousand pure platinum cannot be marked with the word platinum or any abbreviation thereof.

Copies of the Platinum Guide Federal Register notice and the entire Jewelry Guides are available from the FTC's web site at http://www.ftc.gov and also from the FTC's Public reference Branch, Room 130, 6th Street and Pennsylvania Avenue, N.W. Washington D.C. 20580; (202) 326-2222

Jurgen

Platinum Alloys,Platinum Jewelry,FTC Platinum Guide,Platinum Jewelry Markings

950/50 Platinum /Cobalt Alloy

Platinum in its pure form is very soft and needs to be alloyed.  These Platinum alloys have different advantages and are used for specific purposes.  The flow properties of the 950/50 Platinum /Cobalt mixtures are best suited for casting.  With this alloy, very fine pieces of excellent quality can be cast, and considerable detail can be achieved.  Pt/Co has an annealed hardness (HV) of 130 and when cold-worked achieves a hardness (HV) of 270.  It polishes well and holds its luster for a long time.  When welded with a torch Pt/Co may oxidize slightly.  This can be removed by firecoating the object after the initial welding and re-heating it to about 1000° F. Pickle in a 10% solution of nitric acid.  The oxidation will not reappear during wear.  It is not possible to torch-weld different Pt alloys together as they have different melting points.  It is always safe to solder them together using 1500 or 1700 solder.  As a point of interest, Pt/Co is slightly magnetic.

Be sure to wear #5 or #6 welding goggles to protect your eyes.

Platinum /Cobalt alloy is slightly ferro-magnetic.  This Pt950 alloy has very good flow characteristics and is a superior platinum casting alloy.  With its good hardness, it takes on a great polish.  The best way to size a Platinum /Cobalt alloy ring is soldering with 1700 solder.  Roll the solder paper-thin, wedge it into a very well fitting seam and heat.  The seam should be very, very thin.  Now use a file to remove excess solder, and BURNISH the seam with a Tungsten burnisher.  This should remove all traces of the seam.  Now polish and clean the ring.

Jurgen

Platinum Alloys,Platinum Jewelry,Casting Platinum,Welding Platinum

Making a Platinum Wire Basket Pendant

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