The major benefit to buying 10k gold is the price savings, because there is less pure gold in the jewelry the price comes down. 10K gold is very hard and resists dings and dents; however because of the lack of pure gold it is very light in color. 10K gold tarnishes over time because of the high alloy content and often needs polishing to remove the tarnish from the metal surface. 10K jewelry is considered to be lower quality jewelry. 10K gold is known to cause skin creations because of its high alloy content.
14K yellow gold is very affordable and is a practical choice when choosing yellow gold for jewelry. Unlike 10K, 14K has a warm yellow color, does not tarnish, and doesn't require polishing for tarnish removal. It does ding and dent a little more often than 10K, but polishes more easily because of it's softer surface. 14K yellow gold is sold more often than any other yellow gold.
18K yellow gold is considered to be the highest quality gold that is sold in the United States and Europe. It has a very rich yellow gold and when set with diamonds the contrast between the whiteness of the stones and the richness of the gold creates a beautiful look. It is a bit soft for everyday wear and won't last as long as 14K. 18K is a perfect choice for platinum/18K two tone jewelry because the darker yellow color shows up well against the pure white platinum. Gold's purity level is rated using a karat scale with pure gold being 24K or .999 Fine