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White Gold or Platinum?

Shall I buy an Engagement Ring in white gold or platinum?

First one should know the difference between the two metals, which are very different even though they look the same.

Platinum is the rarest and most precious of jewellery metals. It is only found as white in nature and when it’s refined it’s then melted under high temperature (approx 1800 degrees) and mixed with a small percentage of alloy to harden it, so it becomes suitable for jewellery making. Usually an approximate ratio of 95% pure platinum is mixed with approximately 5% of copper, ruthenium or nickel.
Platinum used exclusively in settings is mixed with less alloy as to not be as hard.

Jewellery made from platinum is heavier than that made from gold and is more dense, also being a more difficult metal to work with during manufacturing (especially handmade jewellery).

Platinum looks very white and when polished up it can look like a mirror, so it's naturally the whitest precious metal.

White gold is not found in nature, only yellow gold is found naturally; and after it’s refined it’s mixed with white alloys, which dominate over the yellow colour of pure gold. The ratio of alloy to gold varies depending on the karat quality required; but say for 18 karat white gold the ratio will be 25% alloy melted with 75% pure gold.

Unlike yellow gold which is usually only mixed with copper and silver, white gold has many different alloy recipes and can vary substantially in the whiteness and quality even with the same alloy to gold ratio. In other words there is 18 karat white gold that is still yellowish and must be rhodium plated to look truly white. This version is the cheapest 18 karat white gold.
A level up from that is 18 karat white gold which is mixed with more palladium and looks greyish white (almost white). After rhodium plating it looks perfect; and the advantage with this gold is that even after the rhodium starts to wear you don’t notice the change much, due to a more whiter gold underneath.
A level up again is a premium grade of 18 karat white gold which has platinum added with the palladium. It’s the whitest of the white gold, but still not as white as platinum - until it’s rhodium plated of course. Platinum can also be rhodium plated but it doesn’t need to be.

Now - to answer the question:

An Engagement Ring made from a good quality white gold is a good choice, but if affordability isn’t the issue then platinum is a better option to go with. Like everything in life there is a trade off somewhere and with platinum the catch is that if the engagement ring ever needed a repair or resize in the future it is more difficult to do; and sometimes resizing can never be perfect (where a small cutting scar remains slightly visible) due to the very high fire temperature required to penetrate platinum. This is only the case when there are diamonds or other gemstones set in the platinum ring, as they may get damaged from too high of a temperature - therefore restricting the jeweller from applying the necessary temperature to complete the task to perfection. If it's a claw set solitaire platinum engagement ring then it's not too diffiucult to remove the diamond from the setting before repairing / resizing, so that way platinum isn't restricted and can be serviced to perfection like white gold. Once fixed / resized the diamond can easily be reset in the claw. As far as tolerating very high temperature goes: Diamonds are the most durable and can take the highest temperature of all other gemstones, but everything has it's limits.

What is rhodium plating?

It’s a very white and bright metal plating that is mainly used for white gold, but is also used to plate silver, yellow and rose gold. When used on white gold it enhances it’s appearance so it looks at least a good as platinum, as even the best white gold without rhodium plating cannot look as white as platinum.
Rhodium plating lasts a long time when not always handled, so for an item like a pendant it will last a lot longer than for an engagement ring, as the latter generally has higher Wear & Tear, being on the finger and usually always worn.

How is rhodium applied?

The procedure to re-plate the white gold engagement ring is to first polish it thoroughly to remove any left over rhodium plating, as the rhodium doesn’t wear equally and will remain in areas that are protected. Once the ring is polished it is then cleaned in an ultrasonic bath; and it’s then electro-cleaned.

After cleaning it is rinsed well in distilled water and dipped in rhodium solution. This procedure can be done safely and frequently when necessary.

Does the diamond/s have to be removed from the setting before rhodium plating the Engagement Ring?
Definitely not, as the rhodium plating is only done while all the diamonds or other non-porous gemstones are in the setting. Rhodium plating is the final stage of finishing the white gold item, so the engagement ring / jewellery cannot be scratched after it’s plated, otherwise it has to be re-polished, re-cleaned and re-plated.
The rhodium does not stick to stones; it only sticks to precious metals after it’s activated with a small voltage.

How is the voltage applied?

Inside the rhodium solution bath is an anode that’s hooked up to a transformer. The engagement ring is lowered into the solution held by a fine copper wire, which is also connected to the transformer - for anywhere between 20 to 60 seconds. Finally it’s removed and washed, as rhodium solution contains harmful substances, such as cyanide.