This is the SECOND MOST IMPORTANT FACTOR to consider when you are buying a diamond.
Unless you are specifically looking to buy a yellow diamond for example sake, gorgeous by the way, we would suggest avoiding hues of yellow or any other colour for that matter.
When considering colour present in diamonds, jewellers will refer to a GIA Scale (The Gemmological Institute of America) that starts at a D Colour Diamond which is a colourless PERFECTLY WHITE diamond, then defends all the way to a Z Colour Diamond which would have a visible yellow or brown hue.
As you can see from the above table, D~F are colourless diamonds, G~H are near colourless diamonds and you certainly wouldn't be able to see any colour with the naked eye.
If your budget allows, we would recommend considering diamonds that are D~H in colour.