I often wondered this myself so I did some searching & this is what I found... hope it helps!!
http://gilletts.com.au/information.php?info_id=39Gold colors
Next you need to consider the color of gold.
Gold is available in several different colors. The most popular is yellow gold, followed by white gold and rose gold, though other gold colors are sometimes also available such as bronze, red and lime gold.
Jewelry can also be made using a combination of different gold colors. These jewelry items are sometimes called two-tone, three-tone or multi-colored gold.
The gold content of yellow gold is measured in the same way it is measured in for example white gold. So an 18kt white gold ring contains 75% pure gold, just as 18kt yellow gold contains 75% pure gold.
The difference in color between yellow, white and rose is determined by the metals used in the alloy mix.
As the color difference is due to the metal components in the alloy mix, the color of yellow gold and rose gold will not chip, fade or wear off with age.
Yellow gold is made by mixing pure gold with alloy metals such as copper and zinc.
Rose gold is made using a mix of pure gold with alloys including copper. The copper provides the rose-reddish color.
White gold is an alloy of gold and some white metals such as silver and palladium.
Traditionally nickel was used in white gold, however, nickel is no longer used in most white gold made today as nickel can cause reactions with some people. We do not use nickel in our white gold
When white gold rings are new they can be coated with another white metal called Rhodium. Rhodium is a metal very similar to platinum and rhodium shares many of the properties of platinum including its white color.
The rhodium plating is used to make the white gold look more white. The natural color of white gold is actually a light grey color. The rhodium is very white and very hard, but it does wear away eventually. To keep a white gold ring looking its best it should be re-rhodium plated approximately each 12 to 18 months. Most local jewelers are able to rhodium plate jewelry for a cost effective price.
As each gold color contains the same proportion of pure gold all gold colors with the same carat weight when measured on the Vickers scale have the same Vickers score.
There can be a difference in color between the different carats of gold.18kt yellow gold is more yellow than 9kt yellow gold with 18kt yellow gold having a richer golden color making 18kt yellow gold a more popular choice of yellow gold than 9kt for ladies engagement rings.
9kt rose gold has a darker rose-copper color than 18kt rose gold which has a more subtle rose color.
9kt white gold and 18kt white gold have a similar white color (as normally both have a rhodium plating finish.
When comparing the price of the gold colors in the same carat, white gold is normally a little more expensive than yellow gold and rose gold. Yellow gold and rose gold normally have approximately the same price.
When trying to decide between the gold carat types there are three things to consider.
The metals performance with every day wear
The difference in color between the 9kt, 14kt and 18kt gold
The difference in price between the gold carats.
In practical terms, 18kt generally holds up to everyday wear better than 9kt and tends to look better than 9kt as it ages over the years. This is one of the reasons why 18kt is normally preferred for ladies engagement rings rather than 9kt.
18kt is the superior metal for lady's and men's wedding rings provided that the ring is not a lightweight construction (Gillett's Jewellers rings are a good construction). However, 18kt is more expensive than 14kt and 9kt, which is usually fine for ladies engagement rings, though in a large men's ring the 18kt price can be a noticeable difference.
9kt, 14kt and 18kt are each suitable equally suitable for use in dress rings, earrings, pendants, bracelets and necklaces. Many people choose 9kt and 14kt for their earrings and pendants due to its lower price.
by bobaroxthesox on Wed Mar 26, 2008 12:32 pm 
