With hairpieces, a customised colour is pretty much essential in order for the hairpiece to blend seamlesslely and naturally with the wearer's own hair.
There is an exception - sometimes people naturally have hair that does not have multi-tones. Good examples of this are people whose hair is colour 1 or 1b.
A good way of making a nice blend or mix is to combine several shades within a certain colour range, e.g. 6, 8, 10. You will find some references online for colour blends if you want ideas to get started on creating your own color mixes (hint: take a look at sheitel sites to find examples).
Here's an example of one of mine using 8 and 10 virgin European human hair.
|8/10 Human Hair Colour Mix|
The 10 is raw hair which has a range of tones within it because it came from one donor. The 8 is purchased, so the colour is more consistent strandwise, but there is still variation within the strands.
You can choose to blend all the colours you select in order to create an overall new colour or you can choose to create a high-lighted or low-lighted effect. I chose to add low-lights by putting the darker tone over the lighter hair.
As you can see, the darker tone occurs in small sections like low-lights sometimes do (although you can of course choose to do chunkier sections if you wish). In order to add low or high-lights, you can do this by ventilating selectively as you reach the upper layers of your hairpiece or wig. Another option is to add them via dyeing the hair after making the wig/hairpiece (as you would do in a salon). The downside being the hair is no longer virgin. If it was not virginmhair to start with, you may not always get the result you expect when dyeing as you do not know how the hair has been treated before younlaid your hands on it.
If you wish to create a blended/entirely new colour, you can do this by passing all the shades of hair through a hackle. For an example of this, have a search on YouTube - there is a video of a gentleman blending synthetic hair using a hackle. If you do not have a hackle, another option is to place all the shades in your drawing cards and take a little from each shade as you work (although this will appear far less blended than if you use an actual hackle).