Sizing Up: Platinum Alloy Ring with Diamonds in the Shank Using a Torch

Quality Assurance Benchmarks highlight the workmanship of semi-finished and finished jewellery. Learn how to evaluate the quality of a platinum alloy ring with diamonds in the shank that was sized up using a torch.

Perspective view of a platinum ring with diamonds set in the shank

Ring is round

Finger size is accurate

No excess solder around the solder joint

No pits or visible solder joints

Original shape and shank dimensions are maintained

Shank contour is evenly proportioned and the ring is well finished, with no sharp areas

No tool marks

Piece has a high, bright, even lustre with no colour difference between the added piece and the ring

No damage to the diamonds

All diamonds are tight and secure

Potential Problems and Engineering Features

Sizing Stock Alloy Options

Tweezers are used to insert platinum sizing stock into a ring held on a mandrel

The alloy mixture in this ring is specific to a design and manufacturing company in North America. It’s made of 950 platinum combined with ruthenium and palladium. In this case, it is necessary to get sizing stock directly from the company that uses this particular alloy, which is different from commercially available sizing stock.

It is vital to match the platinum alloy of the insert with the alloy mixture of the ring. Colour, compatibility and the visibility of solder junctions are common problems when alloys don’t match.

Jewellery manufacturers generally make platinum jewellery with commonly available platinum alloys. An internationally accepted standard for jewellery is a mixture purity of 95%, or 950 parts platinum and 50 parts other metal/metals.

The most common alloys are 950 platinum/50 ruthenium and 950 platinum/50 cobalt. There’s also a wide range of other mixtures.