Platinum

Jewelry platinum is usually Platinum 950: 950 parts in every thousand are platinum, and the rest are other platinum-group metals, such as iridium or ruthenium. Pacific Jewel’s platinum is Platinum 950.

In the United States, only metal that is at least 950 parts per thousand platinum may be called simply “platinum”. Lower purities have to carry their number, such as 900Pt or 850Pt.

Platinum does not tarnish, and it keeps its natural white color. Its white is the metal itself, not a layer on top of it.

It needs no plating to stay white. White gold is usually plated with rhodium for its bright white, and that plating wears away gradually and is renewed from time to time, more often on a ring worn every day. Platinum has its bright white finish without plating, so there is no layer to wear through.

The feel of it. Platinum is very dense: by the studio’s own figures, the same ring weighs about 1.6 times as much in platinum as in 14k gold, and about 1.3 times as much as in 18k. That weight is part of how a platinum ring feels on the hand.

How it wears. A scratch in platinum moves the metal aside rather than removing it. Over time the surface takes on a soft satin sheen called a patina. You can keep it, or a polish takes it away and brings back the mirror.

GIA calls platinum hypoallergenic. And a white metal can make a colorless or near-colorless diamond look more colorless; white prongs do this even on a yellow gold band.

The weight: about 1.6 times the same ring in 14k gold. On a wide band, that is a ring you feel.

The patina comes back. A polished platinum ring takes on its satin sheen again with wear, so a mirror finish all the time means a polish now and then.

More bench time. Platinum melts at 1,768 °C, against 1,064 °C for gold, and finishing it to a mirror polish takes longer. GIA notes that while platinum currently costs less than gold, the labor for platinum jewelry costs more.

Anyone who wants a white ring with no plating to renew, anyone who likes a ring with some weight to it, and anyone setting a colorless or near-colorless diamond, which a white metal can make look more colorless. GIA calls platinum hypoallergenic, which matters to sensitive skin.

The Design Studio weighs every design from its real geometry, with each metal’s density: Platinum 950 at 20.7 g/cm³, against 15.6 for 18k yellow gold and 13.1 for 14k. That is why the same ring weighs about 1.6 times as much in platinum as in 14k, and about 1.3 times as much as in 18k. Pure platinum is denser still, 21.45 g/cm³.

Choose platinum for any design in the studio to see its weight in grams and pennyweights, then switch the metal to see the same ring in gold.

Platinum’s price per ounce fell below gold’s in January 2015 and has stayed below it since. A platinum ring holds more metal by weight than the same ring in gold; the line above weighs the two against each other at the prices it names.

What sets the cost of a platinum piece: the weight of metal, the extra bench time platinum takes, and, separately, the stone.

Clean it in warm water with a drop of dish soap and a soft brush, rinse, and dry with a lint-free cloth. Pacific Jewel rings come back to Sara for a clean and an inspection whenever you like.

The patina is normal. A polish takes it back to a mirror whenever you want it. Platinum that has not been plated never needs re-plating.