The right stuff - How to choose the right metal for your ring

GOLD

In the karat system, pure gold is expressed as "24 karat fine" (24K). The gold content of any gold article depends on the proportion of pure gold it contains. In its purest form, 24K is too soft to withstand the abrasions usually associated with daily wear, so it is alloyed with other metals to give it strength.
The color of gold is determined by the different alloys that are mixed with pure gold, ie: copper alloy = pink gold, nickle and /or palladium=white gold. Each of these alloys alters the color.
Historically, white gold was introduced to replace Platinum. White gold can resemble Platinum, but the two have very different properties and prices.
19 karat white gold is the whitest of all and due to the special new metal alloy does not need to be rhodium plated. Traditionally, white gold is plated with Rhodium, giving definite, chrome white appearance, the piece then looks similar to Platinum, is durable and cheaper than Platinum.
The gold content in white gold is equal to its comparative yellow gold karat, in that, 18K white or yellow gold each contain 75% pure yellow gold.

PLATINUM

Platinum is the only precious metal used in fine jewellry that is 90% - 95% pure. is hypoallergenic, and tarnish-resistant. Platinum jewellry is usually stamped 900pt, 950 Plat, or Plat. While it is the stonrgest of jewelry metals, it does scratch and develop a patina of wear. Many people prefer this look, unique to Platinum. Platinum can be re-polished to bring back the original finish.

WHAT IS THE DIFFERENCE BETWEEN PLATINUM AND 18K OR 19K WHITE
GOLD?

Platinum is a naturally white metal. 18K white gold is, actually, yellow gold that has been alloyed (mixed) with another metal. 18K white gold is plated with rhodium in order to keep its Platinum like luster. Over time this plating wears off (yellowing) and has to be re-done. How long depends on the frequency of wear, skin acidity, and the thickness of the rhodium plating.
19K white gold contains special metal alloys that make it the whitest ofwhite golds and is often confused with Platinum. 19K white gold does not need to be rhodium plated and is naturally a clean, crisp white.
Platinum is a tougher metal unaffected by common household chemicals and, unlike gold is not damaged by chlorine, bleach or detergents. Platinum though tough still has to be alloyed with stronger metals to prevent bending.
The cost of platinum jewelry is higher than gold because of it purity. Cost of repairs is higher as well because it takes specialized tools and skills to work in Platinum.