ABI Precious Metals in Carson, California, invented a metal mixture containing four precious metals in the alloy: silver, palladium, gold, and platinum. Though ABI doesn’t disclose the actual chemistry, they allow purchasers freedom to call the metal whatever they wish!
Star Ring, Inc. of California trademarked Platina 4 as the name for this alloy mixture and chose P4 to stamp the ring shank. A P4 SR stamp on a ring represents Platina 4 made by Star Ring.
The metal was created as a lower-price-point alternative to karat gold. The inventor claims it’s hypoallergenic, easy to clean, and very durable. However, due to the off-white color of the alloy, when overseas manufacturers cast it, they often plate it with all sorts of white metal, including nickel and chromium. This creates headaches for jewelers when it comes to sizing and fixing broken prongs because the coatings render the metal brittle during heating.
But there is a solution! Since P4 is essentially a silver-based alloy, silver solders can be used during assembly, and sterling silver sizing stock can be used for sizing the P4 ring.
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