Certain metal colours look better on certain skin tones. To help you select the right metal that suits your skin tone, you have to identify if your skin tone is warm or cool. There is a basic test to determine if your skin tone is warm, cool or natural in certain cases.
In natural light, look at the veins on your arm to help determine this. Your wrists are usually an easy place to look at first. If you are cool, your veins will usually have a blue tinge to them. If you are warm, your veins will have a green tinge to them.
View the image below to assist you: