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Quality Assurance Benchmarks highlight workmanship of semi-finished and finished jewelry. Learn how to evaluate the quality of a platinum cobalt ring with channel-set diamonds in the shank that was sized down using a laser welder.

Side view of platinum solitaire. Design features a princess cut center stone set in v-prongs, two princess cut, bezel-set side stones in the gallery, and princess cut, channel-set stones down each side of the shank.

Finger hole is round.

There are no pits, visible solder lines or excess solder

Shank’s shape and original dimensions were maintained.

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

There are no tool marks.

The piece has a high, evenly bright luster.

Perspective view of platinum solitaire. Design features a princess cut center stone set in v-prongs, two princess cut, bezel-set side stones in the gallery, and princess cut, channel-set stones down each side of the shank.

Ring size is accurate.

There are no pits, visible solder lines or excess solder.

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

There are no tool marks

All diamonds are tight and secure.

Potential Problems and Engineering Features

Chamfer the ends of the shank and adjust them so they are in full contact prior to welding.

Platinum ring shank with chamfered ends that are in full contact

Chamfering lets laser pulses completely penetrate the central portion of the joint. Platinum cobalt laser wire will be used to fill the joint.

Each chamfer angle is about 45°. This angle allows the laser to penetrate and access the joint’s core area.

Before welding, the ring might not be round. Final rounding is done after welding.

Side view of a platinum solitaire ring on a ring mandrel where gaps around the ring indicate that the ring is out of round.

Attempting to round the ring prior to welding could cause damage to the channel-set princess-cut stones.

How-to Video

Sizing Down a Platinum Cobalt Ring with Diamonds using a Laser Welder

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Tool and Topic Related Info

After lasering, the joint should look like this. The joint was chamfered and its inner portion was bonded using the laser, and then the joint was filled and joined using platinum wire and the laser.

Platinum ring shank joint, overfilled with platinum cobalt after laser welding.

The initial pulses from the laser bonded the shank metal at the core of the joint.

The joint was overfilled using 28-gauge platinum-cobalt wire.

Overfilling will allow for smoothing and blending of the joint without changing its original dimensions.

After welding and filing the sizing joint, push the ring down firmly on a ring mandrel to round it. Tap lightly on the sides of the ring where no gemstones are set. Turn it on the mandrel and repeat. If it’s still not completely round, consider using a ring stretcher.

Use very slight and small pulls to round the ring. Stretching too much will cause the ring to tear, crack, become too large, and loosen the stones. This rounding technique should be the last step in the process and used only if necessary.

Because platinum lacks memory, the stretching motion of a ring stretcher will help round it and, if carefully done, not increase its size.

Featured Quality Assurance Benchmarks

Sizing Down: Platinum Cobalt

Sizing down a platinum cobalt ring using a torch

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Determine Finger and Ring Size

Learn how to determine finger and ring sizes accurately

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Prefinishing Platinum

Prefinishing: Best practices for prefinishing platinum

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Prefinish and Finish Platinum

Evaluate a prefinished, polished, and buffed platinum ring

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