Platinum, White Gold, and Silver all look very similar to the eye. However, these three metals are all quite different, with different properties.
Wait, how can gold be white?
Platinum, Palladium, and Silver all naturally have a shiny white appearance. Yet pure gold has a yellow appearance. So how can they all be "white"?
Except for fine jewelry (fine gold and silver), all jewelry metals are not pure metals but a mixture of metals. These are called alloys. The precious metals are simply too soft, when pure, to last the test of time as jewelry. We add other metals such as copper, silver, and rare-earth elements to improve the hardness and durability – these additions can also change the color.
In large quantities, adding palladium and nickel to Gold makes the resulting alloy white. Zinc is also added. Similarly, adding a large amount of copper turns gold a rose color.
So how much gold, platinum, and silver are in each piece of jewelry?
Hallmarks or Stamping tell us the proportion of each precious metal in a piece of jewelry when it was tested by the company or an assay office (depending on the country).
It is always important to check the Hallmark or Stamp when buying jewelry. Read here.
For white gold, we commonly see 10K, 14K, and 18K standards (41.7%, 58.5%, and 75% Gold by weight, respectively). Platinum is typically sold at 950 Fineness (95% Platinum by weight). Sterling silver is the most common, at 92.5% Silver by weight.
Why would I choose platinum or white gold over silver?
Silver is commonly used in jewelry, although it has one big issue – it tarnishes!
While some tarnish-resistant silver products are on the market, they are not tarnish-proof; they just slow the rate of tarnishing. A common tarnish-resistant alloy is Argentium.
If silver is looked after properly and regularly, its lustrous appearance can be maintained, and remain a beautiful piece of jewelry.
Which is shinier? How long will it last?
Shine depends on how well a metal reflects light. Platinum is naturally whiter and shinier than white gold. 18K white gold is less white than lower karats (the more gold, the lower the content of "bleaching" metals). It is also important to note that White gold is sometimes plated with rhodium and so can appear brighter than Platinum, although not forever! (see below)
How long this initial appearance lasts depends on how quickly they wear and scratch. A scuffed ring will appear less bright and shiny than a new one.
Wear is, scientifically, quite complicated. White gold is harder than platinum, so that it will scratch less quickly. However, scratching leads to mass loss in white gold, while in platinum, it does not.
So, in short, white gold will scratch less easier and so stay shinier, but it will gradually become smaller (and lighter) over time due to a loss of gold during wear. In any case, the mass loss is only noticeable after decades of wear.
Either way, both 14K White gold, and 950Pt alloys are very popular choices.
Which is more durable?
While white gold is harder than platinum, it is less durable. Platinum jewelry generally wears slower than white gold. Furthermore, platinum is less malleable (it can be deformed less easily) and so it is less likely to be bent out of shape.
Platinum is a popular choice for gem settings because of its higher durability.
Which one tarnishes less?
Tarnishing is due to the reaction of the metal with chemicals in the local environment (such as human perspirant, household cleaning agents, etc., food). This leads to the formation of harmless sulfides and oxides on the surface, forming a thin layer.
Platinum jewelry does not tarnish readily. Because it is 95% platinum, it does not react readily. The jewelry may become duller over time, but this is due to small scratches on the surface, which mean that the jewelry scatters the light.
White Gold alloys are more prone to tarnishing, especially when they are of lower Karat. The non-precious "base" metals such as Nickel and Copper react more readily with elements. 18K and 14K White Gold will not normally tarnish noticeably, but you may see more tarnishing in 10K pieces.
Ultimately, tarnishing isn't a major concern for either white gold or platinum jewelry. If you look after your jewelry, it should be fine!
Do any cause a skin rash (contact dermatitis)?
Some metals react with the skin, and can cause allergies in some people. It is important to note that this is very rarely due to the precious metals themselves, but the alloying additions.
It is not uncommon to be allergic to Nickel. For this reason, palladium-white golds are often preferred to nickel-white golds, but they are more expensive.
Platinum, Palladium and Silver alloys do not cause such problems. Their high precious-metal content, and their alloying additions mean that it is very unlikely to cause any issues. Pure Platinum, Palladium, Gold and Silver are all hypo-allergenic.
Do both form a "patina"?
Due to the difference in how these metals wear (see above), only platinum forms a "patina". As the scratches accumulate, they will develop an "antique" matte finish. You may quite like this (a lot of people do), but if you don't want it, you will need to regularly (annually) polish your piece.
How much do they cost?
The cost of a piece of jewelry includes far more than simply the price of the metal. Buying rom a highly-skilled, reputable jeweler or a more intricate design will cost more.
Typically, platinum jewelry is more expensive. Platinum alloys used in jewelry have a higher proportion of platinum (95% compared to 75% for 18K Gold). Secondly, platinum is denser than gold and so more alloy is needed to make the same size ring. Platinum is also harder to work with because it is less malleable and has a much higher melting point.
How can I tell the difference in the shop?
Platinum is denser than white gold, so identical jewelry will weigh more if it is platinum.
The best way to tell is from the stamp or hallmark. For a guide on hallmarks, please read here.
Be Careful! Plated Jewelry
White gold is often plated with a thin layer of metals such as Rhodium to give it an even brighter appearance. While this may look very nice to start with, it will not last forever. Over time, the plating will wear away and eventually expose the metal underneath. In the case of white gold, the color may be noticeable.
Any reputable jeweler will be able to tell you if the piece is plated or not, and it is always good to ask to avoid surprises.